Up to 9 cm long. Phyllonotus trunculus (Linnaeus) is a similar species (rocher à pourpre in French) and Ocenebra erinacea (Linnaeus) is a smaller one (perceur in French, murice riccio in Italian). Neither of these close relations has a long projecting ‘lip’ like that of Bolinus brandaris. All three species were formerly assigned to the genus Murex. This murex was the source of a famous purple dye in antiquity – see note below.