Description: Arca imbricata Bruguière, 1789 - exterior of right valve of the mossy ark, 2.15 cm across at its widest. Family Arcidae (Jurassic to Holocene) - the ark clams are filter feeders, principally inhabiting shallow, warm- to cold-water marine settings. Date: 15 February 2011, 18:59. Source: Arca imbricata (mossy ark) (San Salvador Island, Bahamas) 1. Author: James St. John.