Alex Mustard / Backlit detail of branching fire coral (Millepora alcicornis) showing the hair like polyps, filled with stinging nematocysts. East End, Grand Cayman, Cayman Islands. Caribbean Sea.

Christian Ziegler / Fire Coral (Millepora alcicornis) growing directly beneath Red Mangroves (Rhizophora mangle), Bastimentos Marine National Park, Bocas del Toro, Panama

Christian Ziegler / Fire Coral (Millepora alcicornis) growing directly beneath Red Mangroves (Rhizophora mangle), Bastimentos Marine National Park, Bocas del Toro, Panama

Christian Ziegler / Fire Coral (Millepora alcicornis) growing directly beneath Red Mangroves (Rhizophora mangle), Bastimentos Marine National Park, Bocas del Toro, Panama

Pete Oxford / Fire Coral (Millepora alcicornis) with fine hairs that contain nematocysts which sting on contact, Belize Barrier Reef, Belize

Norbert Wu / Fire Coral (Millepora alcicornis) a hydrocoral, stings fiercely on contact, Caribbean

Norbert Wu / Fire Coral (Millepora alcicornis) stings fiercely, takes many shapes- note stinging bristles, Caribbean

Norbert Wu / Fire Coral (Millepora alcicornis) stings fiercely, takes many shapes- note stinging bristles, Caribbean

Christian Ziegler / Fire Coral (Millepora alcicornis) growing directly beneath Red Mangroves (Rhizophora mangle), Bastimentos Marine National Park, Bocas del Toro, Panama