Fire corals belong to which genus?

Fire corals belong to the genus Millepora.

Despite their coral-like appearance, Millepora species are hydrozoans, relatives of Hydra, rather than true stony corals. They build hard, calcium-carbonate skeletons and live as colonies attached to reefs and other firm surfaces.

The name “fire coral” refers to the painful burning sensation caused by contact with their microscopic stinging structures. Colonies may grow in branching, plate-like, or encrusting forms, and their colors commonly include yellow, orange, brown, green, and blue.

A common mix-up is confusing Millepora with Acropora, a genus of true reef-building stony corals. Millepora has a distinctive life cycle involving tiny medusae, which release eggs and sperm before the resulting planula settles and develops into a new colony.