there are over 100000 species of mollusks, more than twice the number of vertebrate species! Despite their diversity. all these animals share three common features; a visceral mass, a mantle, and a foot.
1. Visceral moss. the soft-bodied portion that contains inlcmal organs.
2. foot; the strong, muscular portion used for locomotion.
3. Mantle; the membranous or sometimes muscular covering that envelopes but does not completely enclose the visceral mass. The mantle cavity is the space between the 2 folds of the mantle. The mantle secretes the shell typical of most mollusks.