Festive Murex Shell, Pteropurpura festiva 

Festive Murex Shell, Pteropurpura festiva. Shell collected off the beach of Bahía Concepción, Baja California Sur, October 2019. Size: 5.9 cm (2.3 inches) x 3.0 cm (1.2 inches). Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

The Festive Murex, Pteropurpura festiva (Hinds, 1844), is a gastropod mollusk that is a member of the Muricidae Family of Rocks. The shell consists of six whorls, a moderately high spire with low lines, three varices that are uniquely rolled back, a strong knob, on the body between each varix, a closed, curved, short siphon canal, and an enlarged and oval aperture that have fine dentition (teeth) along the outer lip. The exterior of the shell is white to tan in color, with very fine, dark brown, spiral lines; the interior is white to bluish-white. Festive Murex Shells reach a maximum of 6.7 cm (2.6 inches) in length and 3.4 cm (1.3 inches).

Festive Murex are found attached to rocks and on mud substrate between rocks, or on vegetation in the intertidal zone to depths up to 10 m (35 feet). They range from Central California to Magdalena Bay, Baja California Sur. They are now known in the Sea of Cortez.

Synonyms include  Jaton festivus, Murex festivus, Murex gaza, and Shaskyus festivus.