Shell up to 38 mm (about 1,5 inches) in length, elongate-ovate, body whorl slender or broad, solid, sutures distinct, irregular and shallow. Whorls 5-7, apart from an eroded protoconch, spire whorls flat-sided or weakly convex, sculptured with irregular, broad and weak axial folds which usually weaken on the lower half of the body whorl and may be completely absent in some individuals; fine, almost smooth or minutely pitted or axially striate spiral grooves encircle the shell, striae more prominent at the shoulder of the whorls, numbering from 2-7 on the penultimate and from 1-4 at the shoulder of the body whorl, in addition to 8-12 oblique cords towards the base. Aperture longer than the spire, narrow and smooth within, outer lip thickened and occasionally weakly calloused within, margin of outer lip smooth apart from 3-4 very obsolete denticles anteriorly. Columella calloused, and with 4-5 oblique folds, siphonal canal short and straight, siphonal notch prominent. Olive-brown to dark brown in colour, ornamented with a narrow or moderately broad, white or yellowish-brown sutural band and occasionally a few pale streaks which descend from the sutures onto the band along the axial folds; aperture brown within, columellar folds bluish-white or light violet, parietal wall brown. Periostracum thin and brown in colour.

This moderately common, intertidal species is variable in form, sculpture and colouring. The slender form, which lacks the axial folds and has a broad, white or yellowish sutural band, has been described as M. albofasciata Sowerby, M.jousseaumiana Mabille, M. dolorosa Dall, and M. salinasensis Bartsch.

Gulf of California to the Galapagos Islands and Ecuador. On rocky shores, on a rock and sandy-silt substratum, from the intertidal zone to a depth of 12 fathoms.