Wavy Turban Shell, Megastrea undosa

Wavy Turban Shell, Megastraea undosa. Shell courtesy of the commercial fishermen of the greater Los Cabos area, March 2013. Size: 8.2 cm (3.2 inches) x 7.4 cm (2.9 inches).

The Wavy Turban, Megastraea undosa (W. Wood, 1828), in a gastropod mollusk that is a member of the Turbinidae Family of Turban. They are also known as the Waxy Top Shell and in Mexico as caracol panocha. The shells are large, solid and wider than they are tall, with six to eight sloping whorls that are separated by wavy ridges and the exterior is sculpted by wavy diagonal ridges. The exterior of the shell is tan or brown in color, under a darker, fibrous, periostracum; the interior is pearly white. Live specimens have a thick, ridged, operculum. Wavy Turban Shells reach a maximum diameter of 15 cm (5.9 inches).

Smaller Wavy Turbans are found on rocks just below the intertidal zone. Larger specimens are found in rocky or shale areas, often in Kelp Forests, to depths up to 23 m (75 feet). They range from Southern California to Bahia Asuncion, Baja California Sur. They have not been documented from the Sea of Cortez. Wavy Turbans differ from most Turbans in that they are omnivorous with their diets consisting of algae and surf grass, but they also eat invertebrates such as hydroids and isopods.

Synonyms include Astraea undosa, Lithopoma undosum, and Trochus undosus.