16 Different Types of Shells

Various types of shells along with a starfish on a sand.

One of the best seaside activities is finding beautiful seashells. Early morning walks on the beach are especially memorable when you find a rare beauty that will forever remind you of that particular trip to the beach. Many of us who have a collection of shells want to know what type they are and what creature might live in them.

Seashells are grouped or classified by a system that classifies the animals you would typically find in the shell and not the shell itself. Scientists have split them into seven main groups.

The five types of shells we will cover are:

  1. Gastropoda
  2. Bivalvia
  3. Scaphopoda
  4. Polyplacophora
  5. Cephalopoda

Let’s start by dabbling in the science of Conchology (study of shells) by expanding the different types of shells to discover which species belong to each category. Individual shell types don’t have an official scientific classification system, but some conchologists disagree.

Table of Contents

1. Gastropoda

Gastropoda snail on an old branch.

The study of shells or Conchology forms part of a greater science called Malacology, which studies gastropods exclusively. Gastropod shells were once the home of a snail, a type of mollusk.

Snails grow their shells throughout their lives, and the shells are a part of the actual body of the snail that they can withdraw their bodies into to hide.

The shell is the exoskeleton that protects the soft mollusk. The shell of a gastropod serves many purposes and primarily protects them from predators. It also acts as a muscle attachment, prevents dehydration, and stores calcium.

Three primary layers make up the morphology of the shell. These are all created by the secretions of the mantle of the snail and harden over time. The three layers are the:

  • Periostracum (outer layer) – displays the color and patterns.
  • Tracum (middle layer) – is made of calcium carbonate precipitated into an organic substance known as conchiolin.
  • Shell Nacre (inner substance) – is sometimes shell nacre and other times mother-of-pearl. This layer is in contact with the snail’s body and needs to be very smooth.

For this article, it will be helpful to know a few additional morphological terms:

Aperture: The opening of the shell where the head and foot of the mollusk emerges.

Whorl: A whorl is a single, complete 360° turn in the spiral growth of a mollusk shell.

Apex: The tip of the shell or the smallest few whorls.

With a better understanding of the jargon, let’s look at some of the most common gastropods and a few of their associated species that you will likely come across in your next beachcombing adventure.

Conch

Conch shell over a woven cloth.

Conches are known worldwide for their beautiful shells instead of the snail that may have once lived in them. They inspire images of tropical islands and native coastal tribes blowing on a shell trumpet.

Conch shells are the homes of a wide variety of medium to large-sized sea snail shells. They are characterized as one that has a high spiral and a wavey aperture. Conch’s are beautiful and quite impressive compared to other species on this list.

On beaches of North America, you will most commonly find the queen conch. These abound in the warm waters of the Caribbean and the Gulf of Mexico. The sea snails that occupy conches are highly valuable for their meat, as they are served in an array of dishes, both cooked and raw.

The trade of conches is regulated to protect the species and the ecosystem in which they thrive.

Several shells resemble a conch, but there are very few “true conches” in the Strombidae family. The true conches include the Queen Conch (Lobatus gigas) and the Dog Conch (Laevistrombus canarium).

Many kinds of mollusks can produce pearls. The Queen Conch has been known to produce pearls on rare occasions, and they are particularly prized for their slightly iridescent pink pearls, which are used in jewelry.

Cowrie

Cowrie shell against a gray background.

Cowrie shells are the homes for tiny to large sea snails varying from approximately 5mm to 19mm in length. The Cypraeidae family of marine gastropod mollusks has more than 200 different types and species of cowrie seashells, so they are not hard to find in warm seas.

Some of the various species that fall into this category include:

  • Tiger Cowrie (Cypraea tigris)
  • Deer Cowrie (Cypraea vitellus)
  • Money Cowrie (Cypraea moneta)
  • Purple Top Cowrie (Cypraea annulus)

These shells are usually found on beaches along the warm Indian Ocean, such as the Maldives, Sri Lanka, the African coast from Mozambique to Ras Hafun, and other East Indian islands. Cowrie shell money was vital in the trade networks of Africa, South Asia, and East Asia.

Cowrie shells can be found in a fantastic array of colors and patterns. Their apertures are lined with teeth along the entire length of the opening. The top of the shell is a glossy, rounded oval surface that resembles porcelain.

They have been used extensively in jewelry from tribal time to the modern-day present.

Abalone

A bunch of abalones

Abalones are marine gastropods that belong in the family Haliotidae, which contains only one genus, Haliotis. They have a few common names and are often called ormers or sea ears. In New Zealand, they are known as Pãua, and in South Africa, they are called Perlemoen.

The common name for abalone breeds is derived from their color. Species you frequently find include:

  • Pink Abalone (Haliotis corrugata)
  • Green Abalone (Haliotis fulgens)
  • White Abalone (Haliotis sorenseni)
  • Red Abalone (Haliotis rufescens)
  • Paua Abalone (Haliotis iris)

Abalone shells are among the more common that you can find on beaches around the world. These shells have a low, open spiral whorl and are identifiable by several open holes in a row near the shell’s outer edge that the snail will draw water through to breathe.

The inner layer of the shell is thick and is made of nacre (mother-of-pearl). The highly iridescent mother-of-pearl creates a range of solid and pearly colors, making the shells attractive to many cultures for use in jewelry, a unique inlay in musical instruments, and other decorative objects.

Abalones usually live in shallow water, often attached to rocks using a strong muscular foot to keep them safely secured. These creatures are harvested as these feet are edible, and their shells are valuable too. The flesh of abalones is served as a delicacy, either raw or cooked by various cultures.

The over-fishing of abalones has resulted in highly regulated trade and harvesting around the world.

Murex

Close-up of murex on a sand.

Murex is a medium to large-sized predatory tropical sea snail from the family Muricidae. These marine gastropod mollusks are carnivorous and are commonly called “rock snails.” Most Murex species live among rocks and corals in the shallow subtidal zone, preying on other mollusks.

The majority of these are tropical, but they occasionally can be found in polar regions.

Murex seashells are relatively easy to identify as they have distinctive shapes and interesting spikes. They are very popular trophies for collectors around the world because of their unique appearance. Although not as common as some species on this list, they have a vast range.

They might plainly be colored for the most part, but they have shapes that make up for this. Special features they will often boast are elongated, highly sculptured shells, knobbly whorls, and delicate spines.

Bolinus brandaris, originally called Murex brandaris,  commonly known as the purple dye murex or the spiny dye-murex, was historically used to dye fabric by extracting the pigment from the snails mucus.

Some other murex species include:

  • Venus Comb Murex (Murex pecten)
  • Murex Alabaster (Siratus alabaster)
  • Caltrop Murex (Murex altispira)
  • Regal Murex (Phyllonotus regius)
  • Murex Haustellum (Murex haustellum)
  • Woodcock Murex (Murex scolopax)

Volutes

A volute snail sitting on pebbles.

Volutes (meaning “scroll” in Latin) are identifiable by distinctively marked spiral shells occupied by a medium-sized sea snail. There are over 200 species of volutes, and all of them are carnivorous. They live in muddy or sandy bottoms in deep waters in tropical seas.

The shells have an elongated aperture in their first whorl and an inner lip characterized by several deep plaits.

They have a spiral vase-shaped shell with a polished knob at the apex or tip. The elaborate decorations of the shells make them a sought-after collectors’ item, with the Imperial volute (Voluta imperialis) found in the Philippines being especially prized.

Species of volute seashells include:

  • Imperial Volute (Cymbiola imperialis)
  • Hebrew Volute (Voluta ebraea)
  • Volute Lapponica (Harpulina lapponica)
  • Philippine Melon (Melo diadema)

The giant snails in the volute family are also called melon shells and bailer shells.  The empty shells can hold large amounts of water and were often used by sailors to bail water out of their boats. The shell of the species such as Melo amphora can grow to 50 cm (19.7 inches) in length.

Melon shells have a very rounded shape that resembles a melon, and their peachy-orange color also adds to this name. It is rare to find many of these shells since the species live in deep water. They will rarely wash up onto the shore, and you will have to go diving to find these shells.

Some of the Melon & Bailer species include:

  • Giant bailer 
  • Crowned bailer
  • Southern or Milton’s Bailer (Melo miltonis)
  • Umbilicate Melon (Melo umbilicatus)

Miter Shells

Miter shell against a light blue background.

Mitra is a vast genus of medium to relatively large predatory sea snails that belong to the Mitridae family. This genus is named after the bishop’s headgear (the miter) because they have a similar shape and are favored by collectors for their unique shape.

These tropical sea snails create shells considered attractive by shell collectors. The shells are solid, high-spired, and often come in many bright colors with various spotty or lined patterns.

These shells have a thin and pointed spire with a long, narrow aperture. These shells are native to the tropical Indo-Pacific region, where they are easy to find in the intertidal zones burrowed into the sand or under rocks. The miter snail that lives in this shell prefers to live and hunt in coral and sandy areas.

Some of the other miter shells include:

  • Episcopal Miter (Mitra Mitra)
  • Pontifical Miter (Mitra stictica)

Drupe Shells

The species found living in Drupe-type shells belong to the family Muricidae and are commonly called rock snails. They are small, predatory sea snails that feed on other tiny invertebrates. They are inhabitants of the beaches along the East Indian Ocean.

Although they are pretty common to find while beachcombing, they are nevertheless beautiful shells to add to a collection.

Drupes are thick seashells with a large body whorl. Each whorl is covered in bumps called nodules that are a different color (usually dark brown or black) to the background shell (lighter color). This creates a unique and easily identifiable texture.

The inside of a drupe shell is toothed and usually colorful, typically boasting a purple, pink, or peach color aperture.

Auger Shells

Auger shell against a light blue background.

Auger snails species come from the Terebridae family consisting of more than 400 known species around the world. Augers vary in size from small to large and are all carnivorous marine gastropods. These shells are easily recognizable by the high spire of whorls that makes them look like screws or drill bits. 

Some of them have much more ridged and pronounced whorls.

The auger snails are sand-dwelling and live in warm seas. Augers are very clever hunters, and some of the species use a poisonous barb to immobilize the marine worms they typically prey on.

We find any of the auger shells are light shades of tan and brown, which could help them camouflage in the sand, but they can also have brightly colored shells.

Auger species include:

  • Terebra salisburyi
  • Partecoste
  • Marlinspike Auger (Oxymeris maculata)
  • Combed Auger (Hastula strigilata)
  • Lead-colored Auger (Punctoterebra plumbea)

Olive Shells

Olive snails on a sand beach.

Olive snails come from a scientific family of marine gastropods called Olividae. These sea snails are all predatory and usually eat carrion and bivalves found on the sand beaches. Their shells are smooth, shiny, and oval-shaped, with a very loose resemblance to olives.

Olive shells are commonly neutral colors with fascinating patterns.

Olive snails are found all over the world within subtropical and tropical areas. They live in sand in subtidal and intertidal areas of the sea. They are some of the quickest known burrowers among the sea snail species, and they use this skill to hunt.

They deter predators by secreting a purple dye mucus.

The Lettered Olive, Oliva sayana shells are the state shell of South Carolina. Other species within this genera include:

  • Pointed Ancilla (Agaronia acuminata)
  • Felicioliva kaleontina
  • Vullietoliva foxi
  • Agaronia adamii

2. Bivalvia

Bivalvias on the seashore.

Bivalves are the most abundant type of shell on the beaches of the world. There are at least 10,000 recorded bivalve species. The name is from the Latin, “bis,” which means “two,” and “valvae,” which means “leaves of a door.”

By this description, bivalve mollusks have two shells hinged together that can open and close like a suitcase.

A large portion of the seafood we eat is from the bivalve family, as many of the species are edible. Farmers raise various types of bivalves to mass-produce for the food industry. All bivalve mollusks are aquatic and live in freshwater and seawater.

They are usually found living on a seabed, but some have a powerful foot and attach themselves to rocks.

Depending on the species type, they can live in the ocean’s depths or fresh, shallow streams. It sometimes might be challenging to distinguish between the different species as so many look similar, but some of them stand out from the rest with their unique traits.

Let’s take a look at some of the more common species within the bivalve group.

Clams

A bunch of clams in various colors and patterns.

“Clam” is often the general name given to many bivalve mollusks as they are one of the more common types. While only some clams shells are valuable and worth collecting, they are a lucrative food commodity.

They are also known for producing pearls by coating a foreign body that enters their shell with nacre. Clams are less likely to make pearls than oysters.

Clams are not swimming bivalves, and they attach themselves to something stable or burrow into the sand instead. Burrowing is one of the clam’s unique traits compared to other bivalves like oysters and mussels that attach themselves to a substrate.

The colors and patterns on clam shells vary according to the multitude of species. Some of the species of clams include:

  • China Clam (Hippopus procellanus)
  • Common Cockle (Cerastoderma edule)
  • Bear Paw Clam (Hippopus hippopus)
  • Varnish Clam (Nuttallia obscurata)
  • Cardium Heart Shells (Corculum cardissa)
  • Small Ark Clams (Arcidae)
  • Giant Clam (Tridacna gigas)

Mussels

A bunch of mussels attached to rocks.

Mussels are bivalves of the marine family Mytilidae, most of which live on exposed shores in the intertidal zone, attached to rocks and fixed surfaces using their strong byssal threads (“beard”). They mostly have plain, dark brown outer shells and pearly nacrous interiors. Mussel shells are so common on beaches that they are not collector’s items.

Mussels are essential players in a dynamic ecosystem as they are a food source for many different animals, birds, gastropods, and humans alike. Unfortunately, invasive mussels have recently been introduced that damage native ecosystems in both fresh and saltwater environments.

Mussels are widely consumed and are found on most seafood menus around the world. They are an essential food source and are farmed to produce higher yields for the market.

Other species of mussels include:

  • New Zealand Green-Lipped Mussel (Perna canaliculus)
  • Blue Mussel (Mytilus edulis)
  • Mediterranean Mussel (Mytilus galloprovincialis)

Oysters

Oysters resting on ice.

Several different families of saltwater bivalve mollusks are commonly called Oysters that live in marine or brackish water. In some species, the shells are highly calcified and are usually irregular shapes. Many oysters, but not all, are in the superfamily Ostreoidea.

Oysters are often regarded as a delicacy and can be eaten cooked or raw. This places a high value on the trade of oysters in the food market.

Some types of Pearl oysters, which are not “True Oysters,” are cultivated and harvested for the pearl created within the mantle. Windowpane oysters are collected for their semi-translucent shells, are used to make all kinds of decorative objects.

The common species of oysters include:

  • European flat oyster (Ostrea edulus)
  • Eastern oyster
  • Olympia oyster (Ostrea lurida)
  • Pacific oyster (Magallana gigas)
  • Sydney rock oyster (Saccostrea glomerata)

Scallops

Scallops on a sand beach.

Scallops from part of the family Pectinidae and have many different species within their genera. Scallops are similar to oysters and clams, but the fascinating difference between scallops and other bivalves is their ability to swim.

They swim by clapping their shells together, sucking in water, and pushing it out quickly to shoot them forwards, often in a zigzag pattern.

Scallops are highly prized as a food source, and some are farmed as delicacies in the commercial seafood trade. Scallops are found worldwide, with most species being tropical.

Shell collectors value the symmetric, fan-shaped scallops shells with their often fluted decoration, and bright colors, making them a popular object to collect among beachcombers.

The shells also have an important place in popular culture, including symbolism. Their shape is iconically used to depict a “seashell” and has been used as motifs in art, architecture, and design since ancient times.

Some interesting species of scallops include:

  • Orange Lion’s Paw (Lyropecten nodosa)
  • White Florida Bay Scallops (Argopecten irradians)
  • Sunset Scallops (Argopecten gibbus)
  • Pallium Pectin Seashells (Cryptopecten pallium)
  • Japanese Baking Dish Scallops (Patinopecten yessoenisi)

3. Scaphopoda

Scaphopoda on a textured background.

Scaphopoda shells are commonly called tusk shells and tooth shells because of their unique shape and are not very common to find on beaches. The name is derived from Ancient Greek, meaning “boat foot” or “shovel foot.”

These uniquely shaped marine mollusks are found worldwide and make their home in sandy sediment. The mollusks bury themselves in sand offshore, with only the very tip of their shell sticking out to draw in oxygen from the seawater.

They have openings in both ends of the shell to enable them to burrow into the sediment at one end and breathe from the other. 

The two main Orders of scaphopods to which all the species belong are the Gadilida and the Dentaliida. A few of them are so hard to find that they have not been recorded frequently, and some recorded species may be extinct.

Some species of Scaphopoda mollusks include:

  • Common tusk shell (Antalis vulgaris)
  • Calliodentalium semitracheatum

4. Polyplacophora

Polyplacophora resting on rocks.

The species that belong in the Polyplacophor group are more commonly referred to as “chitons.” Their shells have eight valves, thus giving them another name, “the eight-shelled mollusks.”

These mollusks are beautiful and relatively rare even though they have a worldwide distribution. Most species live in shallow tidal areas and rocky intertidal zones, but some live below sea level at more than 22,000 feet (7000 m).

Chitons have been more associated with algae or other marine plants as many of them have a mossy-looking lining on their shells. This lining is their form of camouflage to keep them safe from predators.

A couple of the species of chitons include:

  • Mossy Chiton (Mopalia muscosa)
  • Lined Chiton (Tonicella lokii)

5. Cephalopoda

Cephalopoda resting on the deep sea.

Cephalopods are better known as squids or octopuses, and only a few of the Cephalopoda species have shells. However, some do like to make their homes inside of shells. All cephalopod species are invertebrates and share specific characteristics like they all have arms or tentacles, none have backbones and all have blue-colored blood.

We will only cover one of the cephalopods that has a shell and can still be found today.

Nautilus

Nautilus lying on rocks.

There are only six living species split between two genera under the Nautilus family. The name of the nautilus is derived from Ancient Greek for “sailor.” The Chambered Nautilus is severely protected to prevent extinction as it is the most well-known species.

The nautilus shell is smooth with a large aperture and a tight whorl that compresses back in on itself. These mollusks swim by projecting their tentacles out of the aperture and propelling themselves forward.

Although it is not a perfect golden spiral, the nautilus shell presents one of the finest natural examples of a logarithmic spiral and is often used in art and literature. Scientists consider the nautilus a living fossil as they have remained mostly unchanged for millennia. 

References:

Outforia: Types Of Shells To Find On Beaches Around The World: Facts, Chart And Pictures

PNGitem: Colors of Conch Shells

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