Small vases or tubes, some tending to barrel shaped. Usually in clumps of 2 to 5, from a common base, or ’budding’ from each other. The whole growth is rarely more than about 30 cm tall. Surface texture is very rough and lumpy, and there are lumpy, irregular growths around the rims of each vase.

Colour when seen underwater is usually black. With artificial lighting it is seen to be a rich, deep red.