Pineapple sea cucumber (Thelenota ananas) on a sandy seabed. This is a relative of starfish and sea urchins, and moves around the seabed feeding on detritus and plankton. It is a large sea cucumber, and may reach a length of some 70 centimetres. It is found throughout the tropical Indo-Pacific region, and prefers relatively shallow water, rarely being found below about 25 metres. It is edible, if bland, and is a delicacy in parts of Southeast Asia. Commercial exploitation has dramatically reduced its population, and it is listed as \Endangered\ by the IUCN. Filmed on the Great Barrier Reef, Australia.