Characters: Colonies are composed of contorted branches, sometimes with flat laminar bases. Stands over 5 metres across and one metre high are not unusual. Corallites are 4-6 millimetres diameter, thick walled and have six thick primary septa. The coenosteum is covered with tall spinules.
Colour: Dark brown, cream or green.
Habitat: Forms large stands on protected horizontal substrates including shallow reefs and lagoons.