Sometimes zooxanthellate. Corals are solitary, free-living, and have a flat base. They have a commensal relationship with a sipunculid worm (Aspidosiphon corallicola) which moves the coral about on soft substrates and prevents it from becoming buried. Tentacles are usually extended only at night. Larvae initially settle on a microgastropod shell which they usually envelop during subsequent growth. Corals have only one corallite which is circular. They have prominent costae.
Pale brown, often with a greenish oral disc.
Always found on soft horizontal substrates at depths of 20 metres or more, usually in association with Heteropsammia cochlea and the fungiid Cycloseris cyclolites.
May be locally abundant (commonly 40 individuals per square metre).
Source reference: Veron (2000). Taxonomic reference: Hoeksema and Borel-Best (1991). Additional identification guides: Veron (1986), Sheppard and Sheppard (1991), Carpenter et al. (1997).
displaying probable distribution of species. Points indicate recorded sightings from OBIS.
Heterocyathus aequicostatus.Philippines.A small cluster.Doug Fenner.
Heterocyathus aequicostatus.null.These corals, the size of a small coin, only occur on soft inter-reef substrates.Clay Bryce.
Heterocyathus aequicostatus.Philippines.With tentacled retracted. The strongly developed costae are readily seen.Pat Colin.