A chiton is a type of mollusk in the class Poluplacophora. There are around 940 extant types of chitons and 430 fossil species, which range in size from small to large. Most chitons live in cold water or tropical regions in hard surfaces, such as under the crevices of rocks. They live exclusively in marine areas. All chitons feature a shell with a girdle ornament; both are mineralized with aragonite.
Chitons are invertebrates that move slowly on a muscular foot, but they can cling to rocks. While most of subsist primarily on algae, bacteria and bryozoans, a few species of chitons eat shrimp and even some very small fish. Seastars, crabs, fish and lobsters eat chitons. Even some humans eat them as well; Trinidadians, Barbadians and American Indians of the Pacific coast are known to eat them.