Cerithium

Cerithium, a genus of Prosobranchiate Gastropods, and type of a large family, Cerithiidae. The shell is rough, naked, spiral, elongated, with many coils, and with an oval oblique aperture which has a short canal in front. The species of this family are numerous (140), most of them marine, but many inhabiting estuaries and brackish rather than salt water; some are found in lakes and rivers. A few belong to temperate climates, but most of them are tropical, and in mangrove swamps they particularly abound. The fossil species are very numerous, and almost all limited to the Tertiary formations. C. vulgatum, over six inches in height, is often seen in Italian markets.