Anadara antiquata (Linnacus, 1758) Antique Ark Shell
20-64 mm. Weakly nodulose ribs, narrow interstices. -» Anterior ribs with a single groove down the middle. (50 mm) Distribution: Red Sea. Egypt . Common from Marsa Alam south, occasional in South Sinai area and Gulf of Aqaba. Never in the Gulf of Suez.
Notes: A. uropigimelana looks quite similar to this shell: both have very narrow interspaces. In A. uropigimelana the anterior ribs have several striae, A. antiquata has only one. In juvéniles it may be difficult to tell if the ribs are striate or bisected. However A. antiquata is usually more elongate and has bumpier ribs. Use your fingernail to test them.

Shell solid, inflated, obliquely ovate, 56.5 mm in height, 73.3 mm in length and 52.1 mm in breadth; sides rather angulated at the upper part, anterior short and rounded, posterior elongate, especially posterior ventral part; ligamental area rather broad and short, smooth, grooves absent; surface covered with a coarse velvety epidermis, and sculptured with about 34 flat radial rids, anterior ribs usually bifurcated by a narrow and shallow groove.
Distribution: Hainan and Taiwan Provinces of China; Tropical Indo-Pacific region.
Ecology: Found in shallow waters.