Decatopecten plica (Linnaeus, 1758)
24-41 mm. —> Five to seven broad, low, smoothly undulating ribs with fine raised closely spaced riblets, no scales. Both ears small, anterior like an equilateral triangle, posterior with long lateral margin. Ventral margin sometimes compressed. LV and RV may have very different colors, RV whiter, LV more colored. Many solid shades of red-brown, coral, cream, and white, as well as patterns of these. (37 mm) Distribution: Common in the Gulf of Suez. Rare elsewhere.
This species is usually described as having five to nine ribs, but I have never seen a specimen with more than seven. The variation in tumidity is greater among individuals than between valves of the same individual.