M. canum has a cylindricalcolumn of about 10mmdiameter, that is wider at the base than it is high when contracted. Cinclides are present on the upper part of the column, and there are four or five whorls of crowded tentacles on the oral disc. Internally, there are forty-five pairs of mesenteries in four cycles radiating from the body wall. This sea anemone is grey, the tentacles sometimes having black tips.