Shell up to 32 mm (about 1,25 inches) in length, elongate-ovate to cylindrically-elongate, sutures prominent and narrowly ledged, smooth, body whorl distinctly constricted at the base. Whorls 6-7, apart from an eroded protoconch, spire whorls flat-sided to weakly convex, sculptured with shallow or moderately deep, sharply incised spiral grooves which are narrow and punctate or striate; in deeply grooved specimens the spiral cords are more elevated, flat or slightly rounded, and number from 5-8 on the penultimate and from 17-25 on the body whorl. The spiral grooves have a tendency to become obsolete in the centre of the body whorl in some individuals, but may be continuous from suture to base in others; fine longitudinal hair-lines descend onto the grooves and cords. Aperture equal in height or shorter than the spire, narrow and smooth within, outer lip moderately thickened and smooth, constricted near the commencement but slightly flaring basally. Columella not calloused but parietal wall occasionally thickened, columella with 5 or 6 oblique folds; siphonal fasciole prominently corded, slightly drawn out and recurved to the left, siphonal notch distinct. Uniformly light to dark tan in colour, protoconch and siphonal fasciole occasionally paler, aperture and columella light tan. Juvenile shells have occasionally pale bands at the sutures.

Kingsmill Islands to Polynesia. This rare species which is seldom collected alive, appears to be confined to the central South Pacific and Polynesia. It has been reported from Japan by Kuroda & Habe (1952), but a misidentification is suspected. M. antoni Dohrn, which is a small, broad and not fully mature specimen of M. testacea, has been described from the Hawaiian Islands, but the species occurrence there remains unconfirmed, although possible. The species is easily recognized by its uniformly tan colour, often telescopic whorls, spiral cords which tend to be obsolete on the dorsal side of the body whorl, constricted base and aperture and recurved canal.