Characters: Colonies may be several metres across and are composed of interconnecting meandering thin walled flabello-meandroid valleys. Valleys are 8-10 millimetres wide and may be up to 200 millimetres high. Usually living parts of colonies are separated by dead basal parts. Valley walls and septa are both thin and fragile. Septa are in three orders, those of the first order are up to 5 millimetres exsert and meet at the valley centre where they may curve and form a columella-like median wall. Costae are exsert. Polyps have fleshy mantles, which form a continuous cover of compact discs.
Colour: Grey, sometimes with pale margins to mantles.
Habitat: Turbid or sheltered reef environments.
Abundance: Rare but conspicuous.
Taxonomic Note: Very distinct species.