A chiton is an oval shaped marine mollusc (related to snails, mussels, and octopuses)in the class Polyplacophora that inhabits the intertidal zone in clear water that does not clog up their gills. There are 1000 known species that range in size from 2 cm to 33 cm. A dorsal (top) shell composed of eight overlapping and articulating segments allows the chiton to roll into a ball for protection. Underneath the shell lies a soft girdle protecting the internal organs and often has unique bristles, scales, or spines used to identify species. A muscular snail-like “foot” moves the animal along rocks while it scraps off algae using its rasping tongue, called a radula, which contains numerous rows of 17 teeth coated with magnetite, an iron oxide. The individual u-shaped valves of their shell often wash up on beaches.