Mollusks are soft-bodied, and most have a prominent shell.
The members of this highly successful and diverse phylum are mostly aquatic and include the familiar scallop , clam , oyster , mussel , snail , slug , squid , cuttlefish , octopus , chiton , and a variety of others. Mollusks occupy habitats ranging from the deep ocean to shallow waters to moist terrestrial niches. Certain mollusks, such as clams, squids, and scallops, constitute important food staples, and molluskan shells are highly valued by collectors. In times past these shells were used as money and today are used ornamentally for such items as buttons and jewelry. There are six classes of mollusks.