Where do seashells come from?

If you have been to a beach, you may have noticed the seashells everywhere. Sometimes, you can’t even walk through the sand without shoes on for the sharp pieces. We know the seashells wash up on shore from the ocean, but where do they come from before that?

Believe it or not, seashells are the outer cases of a special type of sea animal called a mollusk, such as clams, snails and mussels. Mollusks are a type of invertebrate animal, which means it lacks a backbone, and other bones as well. The shell of a mollusk acts as their skeleton outside of their bodies. It helps protect the creatures from predators, strong currents and storms, helps camouflage the animal, and do many other things. Seashells are primarily made of calcium carbonate, a hard mineral, as our own bones are.

The shell comes from a body part that is special to mollusks, called the mantle. It is the outside covering of the soft-bodied mollusk. It secretes the calcium carbonate that hardens to form the shell. The shell grows and gets larger as the animal grows and becomes larger.

The shape and color of shells vary greatly. Mostly, shells serve to protect the tens of thousands of species of marine mollusks. The hues of the shell are often influenced by the diet of the mollusk, but some color pigments also serve an important structural role, helping to reinforce the shell. A shell’s shape, size, and color depend on the animal that made it and the purpose it serves.

Mollusks are divided into many types, but the two major ones are bivalves and univalves. Bivalves are mollusks that have two shell halves that form a whole shell, like a clam or oyster. Univalves have one piece, usually a spiral, that makes up its whole shell, which is usually more elaborate than a bivalve shell. Examples of univalves are conch and nautilus.

When a mollusk dies, its shell is left behind, just as land animals leave their skeletons behind. Sometimes, the shell is used as a home by other sea creatures, such as hermit crabs. When a hermit crab outgrows the shell it has borrowed, it abandons it and finds a larger one to use. Sometimes, the shell washes up on the beach, where we can look at them.