Common name for a marine gastropod mollusc in the family Olividae, also known as olive shells, and with the scientific name Oliva mustelina. The rather elongated shell is oval and cylindrical in shape, with a long narrow aperture and a well-developed stepped spire, which is only a fraction of the entire length of the shell. It is glossy, greyish and creamy in colour, mottled with a pattern of brown wavy lines that run along the length of the shell. In some species, the lines may be so wide that they in some parts join, causing those parts of the shell to become largely brown-coloured. The shell contains a predatory sea snail, that forms its shell by secreting materials, such as calcium carbonate and conchiolin, from cells in the most exterior layer from its mantle, i.e. the dorsal body wall which covers the visceral mass of a mollusc and usually protrudes in the form of flaps. Since in life the mantle almost always covers the shell, it causes the shell surface to become glossy. The Weasel Olive snail is carnivorous and sand-burrowing, feeding mostly on bivalves and carrion, and is known to be one of the fastest burrowers among snails. See also POSTAGE STAMPS.