This species forms colonies which can reach over 1 metres across. The large colonies are usually smooth domes.

The corallites are the largest of the three species in this genus, and commonly have angular walls. They have more septa per corallite than S. radians, which means they are thinner and finer looking. Individual septa cannot easily be distinguished in life. Walls between septa are more narrow.

Colour is uniformly cream to pink and brown, sometimes grey.