Bubble Nutmeg Shell, Trigonostoma bullatum

Bubble Nutmeg Shell, Trigonostoma bullatum. Shell provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, June 2012. Size: 5.5 cm (2.2 inches) x 4.5 cm (1.8 inches).

The Bubble Nutmeg, Trigonostoma bullatum (G.B.Sowerby I, 1832), is a gastropod mollusk that is a member of the Cancellariidae Family of Nutmegs. The shells have a somewhat inflated shape and consist of three to four whorls, a moderately high, well-stepped, spire, and a large aperture with a flared inner lip. The sculpture consists of a series of knobs and fine ridges spiraling along the whorls, crossed by very fine, length-wise, ridges. The exterior of the shell may be white with brown bands, or completely brown; the interior is smooth and white. Bubble Nutmeg Shells reach a maximum of 8.4 cm (3.3 inches) in length and 6.9 cm (2.7 inches) in height.

Bubble Nutmegs are found over and within sand substrate at depths between 30 m (100 feet) and 150 m (500 feet). They range throughout the Sea of Cortez, and south to Columbia. They have not been officially documented as residents of the west coast of the Baja Peninsula, however the shell photographed above was collected on the extreme southwest coast of Baja.

Synonyms include Cancellaria bullata and Cancellaria dalli.