Chitons are oval shaped marine mollusks with flattened bodies, and their shell is made up of eight separate plates or valves.  When the shell plates are lined up together, they resemble the overlapping metal plates of ancient armour and have been called “coat-of-mail shells.”  They are a very ancient lineage of mollusk and fossil evidence suggests that chitons have changed little since they first appeared in the Late Cambrian period (about 500 million years ago).

Chitons, like snails, have a rasp tongue (radula) that they use to scape food off of the rocky substrate, and feed mostly on algae and bryozoans.

The giant Pacific chiton of the Pacific Northwest has eight shell plates but these plates are hidden from view under the animal’s girdle.  This chiton is the largest in the world, growing to 14 inches (36 cm) in length, with a long lifespan up to around forty years.