The length of the shell varies between 60mm and 100 mm. The large, solid shell has roundedwhorls. It is variable in its external morphology, due to the presence or absence of spines. There are both smooth and spiny forms. There are also forms with a morphology between these two extremes. They also differ in the presence of the anterior canal, which is almost non-existent in the smooth forms, but prominent in the spiny forms. These two forms can be found together on the same site. The aperture is subcircular and pearly white within. The simple outer lip is rather thin. The colorpattern of the shell is formed by spiral bands of brown or green over a fawn background. The columella is smooth with a white callus with green edges. The subcircular operculum is calcareous. Its outer surface is white with a slight amount of green.