Chondrocidaris gigantea

Chondrocidaris gigantea, also known as the rough-spined urchin or blade-tipped tiara-urchin, is a species of sea urchin of the family Cidaridae. Chondrocidaris gigantea was first scientifically described in 1863 by Alexander Agassiz.

Description
Chondrocidaris gigantea grows to between 8 - 10 in in diameter, with each of its spines reaching 6 in in length. Its spines contain thorns, allowing for the growth of algae and sponges. In turn, the algae and sponges that grow provide camouflage for the sea urchin. The amount of spines found on this species can vary depending on region, for example those found in Mauritius only have 5 spines while those in Hawaii may have up to 10. The rough-spined sea urchin is primarily an herbivore, with most of its diet consisting of the algae that form on the coral reefs.

Distribution and habitat
The rough-spined sea urchin can be found in the Central Pacific, including Hawaii, New Guinea and French Polynesia, as well as in Mauritius. It prefers coral reefs in water depths deeper than 150 ft. using the surrounding coral as cover.