Characters: Colonies never have extended valleys. Instead they form irregular clusters of fluted thin laminae with exsert costae forming upwardly projecting spires and short walls. Columellae are weakly developed. Septa are smooth or have small teeth. Colour: Uniform or mottled brown, grey or green. Similar species: Pectinia alcicornis, which is distinguished by having more solid skeletal structures, tall spires, well developed columellae, and also by the strong teeth on the costae. Habitat: Turbid water habitats, especially on fringing reefs and in crevices on reef slopes. Abundance: Common