Nassarius horridus

Nassarius horridus, called the horrid nassa, is a marine gastropod mollusk belonging to the family Nassariidae, which includes the Nassa mud snails and dog whelks. Its shell is small, ranging from 8 to 15 mm in length, and has an ovate, somewhat spherical shape covered in spines. The spire is conical and pointed, made up of six or seven whorls, with the body whorl noticeably larger than the rest. Longitudinal folds run along the spire, each bearing regularly spaced, pointed conical tubercles that match the shell’s overall color.

The first row of these spines sits just below the suture, while the last row cuts obliquely across the shell’s base. Between each row of spines, fine, numerous transverse striae are visible. The aperture is white and semilunar, with a thick outer lip lined internally by fine striae.

The columella is nearly straight and is covered by the inner lip, which forms a callosity. The shell’s color is uniform, either a white fawn or a pale orange. This species is found off Durban, South Africa; along East Africa; near Madagascar, Réunion, and Aldabra; and across the Indo-West Pacific, including East India, western Thailand, Papua New Guinea, Indonesia, the Philippines, Indo-Malaysia, the Ryukyu Islands, the Solomon Islands, the Marshall Islands, the New Hebrides, New Caledonia, the Loyalty Islands, Fiji, Tonga, the Samoan Islands, and the Caroline Islands. It also occurs off Australia in the Northern Territory, Queensland, and Western Australia.