Shell up to 50 mm (2 inches) in length, fusiformly-elongate to fusiformly-ovate, solid, sutures distinct, smooth and usually narrowly ledged without being channeled. Whorls 8-10, apart from a worn conical protoconch, first 2-3 post-nuclear whorls sculptured with 4 or 5 finely incised and minutely punctate spiral grooves, grooves becoming deeper on the last 3 whorls and produce feebly elevated spiral cords; cords number from 5-19 on the penultimate and from 25-45 on the body whorl. The punctate grooves become smooth on the last 3 whorls and the pittings are replaced by numerous, fine longitudinal hairlines; the spiral threads become frequently obsolete on the centre of the body whorl. Aperture narrow, equal in height or shorter than the spire, smooth within; outer lip thickened, smooth and occasionally slightly reflected, columella glazed and with 4-6 oblique folds. Siphonal fasciole straight or twisted, siphonal notch distinct. White to creamy-white in colour, ornamented with irregular axial or "L"-shaped, dark reddish brown blotches which occasionally merge on the body whorl and form 2 irregular transverse zones; aperture and columellar folds cream, golden-yellow or orange in colour. Periostracum dark brown, thin, but moderately opaque. Height 43.4 mm; Width 13.4 mm; Height of aperture 20.8 mm

The species is variable in form and sculpture, some individuals being slender and elongate, with telescopic whorls; others are broader and more inflated and approach in form M. chrysostoma Broderip; the spiral threads are few or numerous and frequently obsolete on the centre of the body whorl.

East Africa to Polynesia and the Hawaiian Islands. On reefs, under coral, from the intertidal zone to a depth of 15 fathoms.

Records:
EAST AFRICA: Inhaca Island, Lorenco Marques, Mozambique (van Hoepen coll.). MAURITIUS: Flacq (NMW). INDONESIA: Tjilaoet-Eureun (Dautzenberg, 1935). PHILIPPINE ISLANDS: Luzon (NMW); Matnog, Luzon (BMNH); Boac, Marinduque (Clover coll.: Cernohorsky coll.); Samar I. (DMNH); Cabra I., Lubang I., Mindoro (USNM; MCZ). RYUKYU ISLANDS: S. Kunigami-Gun, Okinawa (USNM). NEW GUINEA: Biak I., Schouten I. (USNM). NEW BRITAIN: Nordup village, Rabaul (McCollim coll.). NEW HEBRIDES: Efate Island (Allan coll.); Teuma Bay, S. Efate I. (AIM). FIJI ISLANDS: Cakaudrove coast, Vamia Levu (Browne coll.). SOCIETY ISLANDS: Huahine (Garrett, 1880). TUAMOTU ISLANDS: Anaa Island (BMNH). HAWAIIAN ISLANDS: Kewalo, Honolulu (AIM); off Makua, Oahu,7 faths. (Clover coll.); off Rabbit I., Oahu, 6 faths. (DMNH).