animalworld:

The Aximoronic SMALL GIANT CLAM
Tridacna maxima
Onexposure /1x.com © Alex Cearns

The maxima clam, also known as the small giant clam, is a species of bivalve found throughout the Indo-Pacific. 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 specimen typically not exceeding 20 centimetres (7.9 in) in length.

The attractive colours of the small giant clam are the result of pigment cells, which have a crystalline structure inside. These are thought to protect the clam from the effects of intense sunlight, or bundle light to enhance photosynthesis, the energy-producing process carried out by the tiny algae living within.

The small giant clam has the widest range of all giant clam species. It is found in the oceans surrounding east Africa, India, China, Australia, Southeast Asia and the islands of the Pacific.

Source: http://en.wikipedia.org/wiki/Maxima_clam

Other posts:

Green Zoanthid Clusters

Giant Green Anemone

Giant Clam - pretty