Astrocoeniidae is a family of stony corals endemic to the waters around Papua New Guinea and northern Australia. Their habitats are steep slopes where strong currents rise from below, in crevices and below overhangs.
These are reef-building colonial corals containing an algae known as zooxanthallae. These algae typically encrust corals up to 20 inches in diameter. On reef slopes, where water is more turbid (cloudy/murky), they are much smaller, only reaching 2 inches across.
The World Register of Marine Species lists 3 genera (Palauastrea, Stephanocoenia, and Stylocoeniella) of Astrocoeniidae and 7 known species.