Angle-mouth Screw Shell, Turritella gonostoma

Angle-mouth Screw Shell, Turritella gonostoma. Shell collected off the beach in the greater Punta Chivato area, Baja California Sur, December 2022.  Size: 12.7 cm (4.9 inches) x 2.8 cm (1.8 inches). Photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

The Angle-mouth Screw, Turritella gonostoma (Vallenciennes, 1832), is a gastropod mollusk that is a member of the Turretellidae Family of Turrets. The shells are solidly built shells of many flat-sided whorls with a small aperture. The exterior is sculpted with fine spiral lines with younger specimens having a spiral ridge in the middle of the whorl that disappears with maturity. The exterior of the shell is gray to purplish brown in color, with white mottling. The Angle-mouth Screw Shell is one of the larger Turrets in the area reaching a maximum of 16.3 cm (6.4 inches) in length and 3.5 cm (1.4 inches) in height.

Angle-Mouth Screw Shells are found on and within mud and sand substrate from the intertidal zone to depths up to 6 m (20 feet). They range from Bahia San Juanico, Baja California Sur to Peru and they are found throughout the Sea of Cortez.

Synonyms include Turritella goniostoma and Turritella punctata.