The Cephalaspidea consists of molluscs with external or internal shells as well as species with no shell. In general
the shells are thin and often transparent. Some like Bulla can accommodate the entire animal in the shell, whereas
in others (Philine, Chelidonura) the shell is reduced and internal. The cephalaspidean head is generally flattened
(cephalic shield) and foot often bearing parapodial lobes which may be used for short swimming bursts. Many
cephalaspideans can be found in fine sand or close to sandy areas, where they burrow to hide. Many species are
carnivorous feeding on small polychaetes, bivalves and foraminiferans.