Despite their amazing diversity, all molluscs share some unique characteristics that define their body plan. All molluscs have a tissue that covers the animal called the mantle, which is sometimes involved in shell secretion and respiration. Molluscs also have a unique set of feeding structures, including the radula, a chitinized strip that bears numerous "teeth", and the odontophore, a cartilaginous structure which provides support for the radula and a place for buccal muscles to attach. The pericardium is another unique structure found in molluscs. It is the remnant of the coelom that contains ducts from kidneys as well as a muscular "heart" that pumps blood.
A detailed exhibit of gastropod anatomy has been prepared by Andrew Zoltan Mason at California State University - Long Beach.
