Shell oval-lenticular, white, fragile and not translucent, with not very prominent apex. Protoconch with only 1 whorl or a little more. There are 6 spiral undulating cords on the nucleus, occasionally interrupted, and one more appears near the suture, so that there are 7 at the middle of the protoconch and 5-6 at its end. The surface between them is irregular, but without microscopic axial lines. The colour of the protoconch is white. Teleoconch with about 1,5 to 1,75 whorls, with a fairly rapid development; it is sculptured by fine axial ribs which are slightly curved; they number only about 14 on the first half whorl, but later they are more crowded and can reach more than 100 on the last whorl. Many fine spiral striae cover the shell and are evident in the interspaces, crossing the ribs to make them appear granular. Aperture ovoid, with the outer lip sharp, only contacting the penultimate whorl for a short distance. Previous whorls and the ends of the crowded axial ribs are visible in the open umbilicus, which lacks a peripheral keel.

The few prominent cords on the protoconch of M. canarreos easily differentiate its shell from that of M. robertsoni, M. garcesi, M. palmalitoris and M. paradoxa. The most similar shell is that of M. worsfoldi, but the latest species has microscopic lines between the cords on the protoconch; also, it has fewer spiral cords on the protoconch. The teleoconch of M. worsfoldi has fewer and more prominent ribs.

Only known from Los Canarreos Archipelago and Cienfuegos.