The Varieties of Seashells

Cockle

• The cockleshell often appears on beaches all over the world. A cockleshell is the home of a small clam that lives in saltwater. This clam is consumed in many cultures, and cockleshells are discarded. When the clams that live in cockleshells die, their shells wash up on beaches. Over two hundred varieties of cockleshells exist, and these are divided into two major categories based on whether or not the shells are ridged. About half of the varieties of cockleshells are smooth, and the other half have rough shells that feature raised lines.

Sand Dollar

• The sand dollar is a shell commonly found on beaches that houses small, flat marine creatures called echinoids. The sand dollar is round and flat and features intricate patterns that resemble carvings. These shells are often found dried along beaches after the animal that resides within dies, and are sometimes picked up by people combing the beach and used as decoration. The sand dollar has a unique circular, flat shape because it is made from five flat plates of calcium carbonate emitted by the echinoid that lives within. The shell becomes increasingly hard and thick over time.

Conch

• The conch shell houses a marine animal also called the conch. A living conch resembles a large, red, muscular snail, and is part of the mollusk family. Conch is consumed in many parts of the globe. In its most common form, the conch shell resembles a handheld trumpet with large bony knobs jutting out in many directions. The shell often has a pink hue and a shiny interior that has been polished by the movement of the snail that resides within.

Scaphopods

• Scaphopods are long narrow shells shaped like swords. They are made from two clamped halves, similar to the shells of clams. The marine mollusks that live inside of scaphopod shells inhabit the ocean floor where they nestle in sand. The scaphopod is part of the gastropod category, which means the sea creature that lives within has a mouth that extends to catch and consume food, and is protected by the shell. Scaphopod shells often wash up and beaches where they appear as long delicate slivers. They are often an opaque gray with darker colored stripes.