Bullia callosa

Bullia callosa, also called the callused bullia, is a marine gastropod mollusk in the Nassariidae family—the same group as Nassa mud snails and dog whelks. Its shell ranges from 18 mm to 50 mm in length, is elongated and cylindrical, and has a smooth, shiny exterior colored like coffee with milk. The pointed spire consists of six whorls that are not convex; each whorl is coated with a layer of material that turns chestnut at the base.

This layer is thickest on the body whorl and extends, widening, to the left lip, where it forms a large, semicircular callosity that is deep chestnut with a white border. A fawn-colored line separates each whorl just below each suture. The ovate aperture is pale fawn, widens toward the middle, and is strongly notched at its base.

The columella is curved, calloused, smooth, and fawn-colored; its callosity is oblique, thick, and furrowed, much shorter than the outer lip. From the lower part of the columella, a groove runs obliquely across the back of the shell, ending at the sharp front corner of the right lip. This species is found in marine waters from Angola to Mozambique.