When dislodged, a chiton rolls into a ball. Beneath the shell is the characteristic molluscan mantle, a fleshy outfolding of the body wall. The lower edge of the mantle, called the girdle, extends below the edge of the shell and aids the foot in gripping. The many gills are arranged in two rows within the mantle, one on either side of the body. The mouth, located on the ventral surface in front of the foot, contains a toothed, tonguelike scraping organ, the radula.
Chitons crawl slowly by means of muscular undulations in the foot.
Most feed at night and shelter under rock ledges by day. Chitons are classified in the phylum Mollusca , class Polyplacophora, order Polyplacophora.