Usually single vases, but sometimes in clumps of two or three, this stiff walled sponge is commonly a transucent white or blue. It may appear to fluoresce (and its surface is so reflective it is not easy to photograph).

The outer surface is heavily ridged with colines and valleys.

Lamarck named this as the genus Spongia. It is illustrated under the genus name Tuba in Duchassaing