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. Prominent side effects can include irritation, stinging or burning pain, erythema (skin redness), fever, urticarian (hives) lesions. These side effects are due to venom released from the nematocyte, as venom is part of the defense mechanism of the fire coral. 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 calcareous 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 calcareous structure of other coral or gorgonian structures.
Within 5-30 minutes following skin contact with fire coral, an immediate burning sensation or a stinging pain develops. A red rash with raised wheals or vesicles appears, and itching develops. Lymph gland swelling may occur over time. Rarely, nausea and vomiting have been reported.
On a failed CON target has the Poisoned condition until they succeed a saving throw. The save can be repeated once per long rest. The save can be replaced by a medicine check. Lesser Restoration spell removes the effect.