Shell massive, solid, of 6-7 whorls, of which the body whorl makes about two-thirds of total height. Whorls with a distinct spiral keel bearing ragged, projecting knobs; and with squamose spiral cords, separated by intervals as broad as the cords. Body whorl with 3-4 larger spiral cords on which the small cords are set close together, and the umbilical chink surrounded by a thickened structure. Aperture ovate, terminating anteriorly in a small, short siphonal canal. Outer lip somewhat thickened inside, with 9-10 denticles extending far inside the aperture.
outside of a yellowish tan color, with dark brown mottles or flames over the spiral cords only, attenuated in the intervals. Inside of aperture white.
common size :
This species is distinguished from other Thais by the peculiar sculpture of squamose cords and the pure white inside of aperture. A similar sculpture may occur locally on the Atlantic species Nucella lapillus, but never with the 3-4 major cords and keel on the body whorl. Mancinella rugosa (Born, 1778) is a different taxon, but Murex rugosus as figured in Born (1780) is as this species, hence the nomenclatural confusion.
BIOLOGY / ECOLOGY
in Indian Ocean under rocks (Bosch et al., 1995); in the Mediterranean, this species has so far been found on hard substrates in a harbour environment.