Galapagos Cowry Helmet Shell, Cypraecassis tenuis

Galapagos Cowry Helmet Shell, Cypraecassis tenuis. Shell courtesy of the commerical fishermen of the greater Los Cabos area, Baja California Sur, January 2011. Size: 15.2 cm (6.0 inches) x 9.2 cm (3.6 inches).

The Galapagos Cowry Helmet, Cypraecassis tenuis (W. Wood, 1828), is a gastropod mollusk that is a member of the Cassidae Family of Helmets. The shell is thinner and lighter than most Helmet Shells and are somewhat egg-shaped, with a low spire. The aperture is narrow but widens as it approaches the anterior end, the shoulder is knobbed, often extending down the body and the exterior sculpting includes both wide bands spiraling down the body whorl and small ridges running the length of the body. The shells exteriors is mottled light and dark brown in color, with varying amounts of white cross-hatching; the aperture can be tan to bright burnt orange; and, the outer lip is often banded with brown and cream or white. The Galapagos Cowry Helmet Shells reach a maximum of 16.8 cm (6.6 inches) in length and 10.2 cm (4.0 inches) in height.

Galapagos Cowry Helmets are found on sand, at depths between 11 m (35 feet) and 30 m (100 feet). They are found in the Sea of Cortez, from Loreto to Cabo San Lucas, Baja California Sur., and along the coast south to Peru, including the Galapagos Islands. They have not been documented on the west coast of Baja.  These shells are considered to be true gems by shell collectors.

Synonyms include Cassis massenae and Cassis tenuis.