Class Polyplacophora (Chitons)Collection Highlights | Updated 5 years ago Ischnochiton torri Image copyright of WA Museum The Polyplacophora’s common name is chitons, with the name of this group meaning "bearer of many plates". A chiton’s shell consists of eight separate plates that overlap to form a shell like a coat of armour along the upper surface of its flat oval body. They have the ability to roll up much like an armadillo as a defence mechanism. In front of the large muscular foot is the small head that lacks eyes and tentacles. However its strongly-toothed radula (a rasp-like ribbon used to tear up food and draw it into the mouth) is tough enough to scrape encrusting algae off rocks. All chitons are marine, and most are rock dwellers in shallow waters and inter-tidal zones. Mollusc (Malacology) Section View the discussion thread.