Tridacna maxima

The maxima clam, also known as the small giant clam, is a species of bivalve mollusc found throughout the Indo-Pacific region. They are much sought after in the aquarium trade, as their often striking coloration mimics that of the true giant clam; however, the "maximas" maintain a manageable size, with the shells of large specimens typically not exceeding 20 centimetres in length.