The crumb-of-bread sponge is a thickly encrusting sponge with a glistening bumpy surface. Specimens found intertidally are bright yellow. Specimens from deeper water are darker. The sponge has been found to have a certain scent, it's been described as exploded gunpowder. The oscula are scattered across the surface of the sponge and may be flush with the sponge surface or on raised mounds. The form of the sponge is variable, depending on its environment. In sheltered areas, branched structures grow from the base. In areas with wave action the surface is convoluted or flat.