any of the marine snails constituting the family Muricidae (subclass Prosobranchia of the class Gastropoda). Typically the elongated or heavy shell is elaborately spined or frilled. The family occurs throughout the world but mainly in the tropics. The many muricids that live in rocky shallows are called rock shells, or rock whelks.
Learn more about murex with a free trial on Britannica.com.