Common Atlantic Abra

Abra aequalis is a small species with plain, white, mostly smooth shells which are slightly round, but triangular in outline. Due to their small size (about 7 millimetres [0.28 in]), A. aequalis is one of several unremarkable, similar-looking species fondly called "little white clams" by amateur shell collectors. The shells are quite thin and fragile, and Robert Parr Whitfield summarized their appearance thus: "it is a very neat and pretty shell, and moderately abundant".

Abra aequalis is found along the southeastern coast of the United States, the Gulf of Mexico, the Caribbean Sea, and the coast of southeastern Brazil. The Global Biodiversity Information Facility records observations from as far north as Long Island. It is abundant along the American coast, around Florida, and is also found around Mexico and the Caribbean Islands. In South America, it is found on the coasts of Venezuela, Suriname, and Panama, as well as on the Brazilian coast from São Paulo to Pelotas. A. aequalis is usually found in shallow waters of depth less than 73 metres (240 ft). It has also been observed on seamounts and underwater knolls. A 1973 study off Sapelo Island, United States, found that A. aequalis became the dominant species in spring. A. aequalis is the most significant food source for Luidia senegalensis in Florida.