Hippopus hippopus-The hippopus clam is incredibly interesting. They have similar care, patterning, and coloration as derasa clams but they have the ability to quickly polish aquariums. Hippopus or bear claw clams also do not extend the mantle past the shell like other giant clams. Feeding on Reef Nutrition Shellfish Diet 1800 (SD Aquarist Shellfish Diet)