These have solitary corallites, reaching several cm diameter. They are short, with disks lying close to the surface, and have typically long and sharp mussid spines which are visible through the fleshy tissue.

Colours range from bright green, reds to dull grey.

While basically a solitary coral, sometimes specimens may divide to form a di- or tri-centric group. If this occurs, the centres stay round and connected, with no tendency to separate as would be seen with a small Mussa.

A third species, S. wellsi, is recognised by several authorities. Dr E Weil’ s photo here (of the single coral) is one he would call S. wellsi. Veron, on the other hand, places all three species into S. cubensis.