An image of Cycloseris erosa coral in Long wave UV Light showing green Fluorescence. This species of coral will glow brightly when illuminated in ultra-violet(UV) light. Corals in the genus Cycloseris are mostly solitary and free living, some attaining 10 centimetres in diameter. The discs are either round or oval and the central mouth, which is surrounded by tentacles, may be a slit. The polyp sits in a calcareous cup, the corallite, and only extends its tentacles to feed at night. It is thought the glow may attract symbiotic algae, or protect the coral from the intense ultraviolet light of the Sun in shallow water. This image is part of a series showing the identical specimen in white light and UV light.