Although mollusks are probably best known for their unique shells, the word itself actually comes from he Latin word for "soft." Beneath their shells, mollusks are actually very soft-bodied invertebrates (no spine) -- and some of the most well-known mollusks (like the octopus, for example) have no shells at all. Mollusks share a mantle (a fold of skin that lines the shell, when present) and a muscular foot that they use for motion. Many types of mollusks are raised and captured for food -- squid and clams, for example -- and some people consider eating snails a true delicacy.