A seashell is the hard, protective outer covering of a sea creature called a mollusk. When you find a beautiful shell on the beach, you're holding what used to be a small animal's home. Just as a turtle carries its shell on its back, creatures like clams, snails, and oysters grow their own shells around their soft bodies.

These shells aren't made of bone. Instead, the animal secretes a special material that hardens into layers, somewhat like how your fingernails grow. Over time, these layers build up into the sturdy shells you find washed up on shore. The animal that made the shell is usually long gone, having died of natural causes or been eaten by a predator, leaving behind only its empty house.

Seashells come in amazing varieties: smooth and spiral like a conch, ridged like a scallop, or long and pointed like an auger shell. Beachcombers love collecting them because each one is unique, shaped by the specific creature that built it and worn smooth by tumbling in the ocean's waves. Some shells show hints of the colors they had when their owners were alive, while others have been bleached white by sun and salt water.