Mollusks are a large group of soft-bodied invertebrates that are widespread in
salt water, freshwater, and terrestrial habitats. Examples of mollusks include
snails, clams, squids, octopus, and cuttlefish.
Most mollusks have a muscular foot and a hard, calcareous outer shell
protecting their soft body, but some, as in the squid and octopus, lack this
type of shell.
