They have a wide range of colours including yellow, brown, green, pink and blue but the most common are whitish-blue.

The corallites are distinct and separate, sometimes raised on cones and sometimes depressed, up to four millimetres across and round in cross-section.

[2] They are found in a range of environments including shallow or muddy waters, as well as deeper areas of the reef where plating forms are most common.

[3] The porous skeleton of these corals provide a home to a variety of polychaete worms that weaken the calcium carbonate structure by tunnelling into it.

In the case of H. stubbingsi, which has a primitive wall and a relatively unspecialised operculum, this may be because it is not equipped to occupy other corals, but the Cionophorus species are smaller and it is an enigma why they are not found elsewhere.