Mollusks (Mollusca, from the Latin mollis "soft") make up one of the great phyla of the animal kingdom. They are coelomate protostome invertebrates, triblastic with bilateral symmetry (although some may have a secondary asymmetry), non-segmented, with a soft body, naked or protected by a shell. Mollusks are the most numerous invertebrates after arthropods, and include such well-known forms as clams, clams, razor clams, oysters, cuttlefish, squid, octopuses, slugs and the great diversity of snails, both marine and terrestrial.