Millepora alcicornis, the branching fire coral (class Hydrozoa, order Anthoathecata, family Milleporidae), is found throughout the Caribbean and tropical Atlantic, forming branching, blade-like, or encrusting colonies with a characteristic calcareous skeleton superficially resembling stony corals. Despite the common name 'fire coral,' it is actually a hydrozoan that secretes a massive calcareous exoskeleton; its powerful dactylozooid polyps armed with nematocysts cause intense burning skin reactions in swimmers. Fire corals are important reef-builders in the Caribbean. Genomic data have been generated for this species and are available in public databases, enabling comparative studies of cnidarian evolution and ecology.