Stichodactyla helianthus is a sea anemone of the family Stichodactylidae. Helianthus stems from the Greek words ἡλιος (meaning sun), and ἀνθος, meaning flower. S. helianthus is also referred to as the 'sun anemone'. S. helianthus is a large, green, sessile, carpet-like sea anemone, from the Caribbean. It lives in shallow areas with mild to strong currents. The anemone crab (Mithraculus cinctimanus) is often associated with it, being found among the tentacles or on the column and margin of the oral disc.