Characters: Colonies are free-living, delicate, thin walled domes, commonly over 0.6 metres across. Septo-costae radiate from a central corallite or are perpendicular to the colony margin. There is usually a well defined line of demarcation where groups of septa meet. Septal teeth are tall. Colour: Dark brown. Similar species: Halomitra clavator. Habitat: Deep protected environments. Abundance: Usually uncommon, but distinctive.