Three-winged Murex Shell, Pteropurpura trialata. Size: 6.7 cm (2.6 inches) x 3.4 cm (1.3 inches). Collection, photograph and identification courtesy of Bob Hillis.

Three-winged Murex, Albinistic Form, Pteropurpura trialata. Shell collected off the beach of Bahía Concepción, Baja California Sur, October 2019. Size: 6.5 cm (2.6 inches) x 3.2 cm (1.3 inches). Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

Three-winged Murex, Albinistic Form, Pteropurpura trialata. Shell collected off the beach at Punta Chivato, Baja California Sur, June 2020. Size: 6.4 cm (2.5 inches) x 3.0 cm (1.2 inches). Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

The Three-winged Murex, Pteropurpura trialata (G.B. Sowerby II, 1834), is a gastropod mollusk that is a member of the Muricidae Family of Rocks, that is also known at the Western Three-winged Murex. The shell consists of six whorls, a moderately high spire with three thin varices which widen and wavier as they approach the aperture, a closed fairly long siphon canal and an oval aperture. The exterior of the shell is white to tan, with numerous dark brown bands, although some specimens are all white; the interior is white. The Three-winged Murex Shells reach a maximum of 9.3 cm (3.7 inches) in length and 4.4 cm (1.7 inches) in height.

Three-Winged Murex are found on rocks, in protected waters, or in water deep away from wave action. They reside in the internal zone to depths up to 130 feet. They range from Southern California to Magdalena Bay, Baja California Sur. They have not been documented in the Sea of Cortez noting that the shell photographed above may extend this range.

Synonyms are Murex trialata and Pterynotus trialatus.