Shell up to 20 mm (about 3/4 inches) in length, roundly ovate to elongate-ovate, biconic and acuminate, spire sometimes slightly concave especially in young specimens, sutures weakly impressed. Whorls 6-8, apart from the protoconch of glassy, white or fawn nuclear whorls, spire whorls generally flatsided and occasionally weakly subangulate at sutures; first postnuclear whorls clathrate, later whorls with prominent, elevated and narrow spiral cords which number from 2-4 on the penultimate and from 9-15 on the body whorl. The interspaces of the cords are deep and "V"-shaped and sculptured with numerous, very fine and generally oblique axial striae. Aperture equal in height or longer than the spire, narrow and smooth within; outer lip thickened in mature individuals, regularly convex and with fluted crenulations at the margin. Columella glazed on the parietal wall, calloused anteriorly,.and with 3-4 oblique folds; siphonal fasciole straight and slightly calloused, siphonal notch distinct. Blood-red, dark reddish-brown or purple-brown in colour, some specimens with pale, whitish spiral cords, tip of siphonal fasciole occasionally darker brown; aperture greyish-brown, columella reddish-brown, columellar folds pale in colour. Height 19.5 mm, Width 9.0 mm., Height of aperture 11.2 mm.

M. tabanula, and the colour form pediculus with white spiral cords, have been separated as species on the sole basis of differences in the exterior colouring. Recent collections of M. tabanula in the New Hebrides, where the species is rather common, showed the colouring to be variable within a population of M. tabanula collected under the same coral rock. The white-corded form pediculus proved to be more common than the uniformly dark brown form, at a ratio of about 3:1. The two colour forms are sympatric in most localities throughout the species range, and the pediculus form was found to be more common in other localities.

Gulf of Aden to Samoa and the Tonga Islands. On reefs, under coral rocks and in crevices of coral, from the intertidal zone to a depth of 8 fathoms.