FIRE CORAL'S
Fire corals are colonial marine organisms that look rather like real coral. Technically they are not corals, since they are more closely related to Hydra and other hydrozoans. The polyps of fire corals are near microscopic size and are mostly embedded in the skeleton and connected by a network of minute canals. All that is visible on the smooth surface are pores of two sizes: gastropores and dactylopores. In fact, Millepora means ‘thousand pores’. Dactylopores have long fine hairs that protrude from the skeleton. Fire corals have a bright yellow-green and brown skeletal covering and are widely distributed in tropical and subtropical waters. They appear in small brush-like growths on rocks and coral. Divers often mistake fire coral for seaweed, and accidental contact is common. Upon contact, an intense pain can be felt that can last from two days to two weeks. The very small nematocysts on fire corals contain tentacles that protrude from numerous surface pores (similar to jellyfish stings). In addition, fire corals have a sharp, calcified external skeleton that can scrape the skin. Fire coral has several common growth forms; these include branching, plate, and encrusting. Branching adopts a calcerious structure which branches off, to rounded, finger-like tips. Plate growth adopts a shape similar to that of the smaller nonsheet lettuce corals - erect, thin sheets, which group together to form a colony. In encrusting growth, the fire coral forms on the calcerious structure of other coral or gorgonian structures.
Photo used under Creative Commons from BBM Explorer