What is fire coral?
fire coral meaning a species of hydroid (Millepora sp.) that frequently is brownish to orange-yellow in color and forms encrusting colonies that can assume the shape of its support structure. Their nematocysts release a virulent toxin which causes painful welts on human skin. Fire corals are not true corals (see Hydrozoa)
Fire coral in the Flower Garden Banks National Marine Sanctuary (Photo: Jackie Reid)
reference: Coral Reef Information System – GlossaryWhat is