Actinodendron alcyonoideum, commonly known as the hell's fire anemone, is a highly venomous sea anemone (family Actinodendridae) distributed across Indo-Pacific reef environments. Unlike most anemones, it has a branched, tree-like body with multiple secondary branches bearing densely packed nematocyst-laden tentacle clusters capable of causing intense pain and skin irritation in humans. It typically inhabits sandy and rubble substrates near coral reefs at depths of a few to over 20 m. It possesses one of the most potent nematocyst-mediated stings among sea anemones. Genomic data have been generated for this species and are available in public databases, enabling comparative studies of cnidarian evolution and ecology.