They can reach considerable size and the best of them display a shimmering optical effect known as 'flame structure'.
This family includes hundreds of species. Giant clams cannot truly appreciated unless seen alive. The shells of most, while impressively large, are a plain, chalky white. The beauty is in the very thick and colourful animal, which pigments of brilliant green, blue, purple and red.
Giant clams filter food from the water but are also “farmers”. Algae living in the clam’s tissue supply it with energy. Organs in the clam’s mantle focus the sunlight so that several layers of algae can grow simultaneously.
Therefore giant clams are found in shallow water with their gapes directed toward the surface and their mantles extended over the edges of the shells for maximum sun exposure. Giant clams are also home to a shrimp, which lives in the mantle cavity for protection.