Characters: Colonies are irregular clusters of fluted flat laminae with exsert costae forming upwardly projecting spires and short walls. Upward projecting spires may be tall, becoming the dominant part of the colony. Columellae are well developed. Costae are characteristically toothed. Colour: Mixtures of greens, yellows and browns with central parts of colonies usually darker than peripheral parts. Similar species: Pectinia paeonia. Habitat: Turbid water, especially on horizontal substrates. Abundance: Usually uncommon.