The stony sponge is a massive sponge with varied shapes. It may be globular, irregular, or cushion-shaped. Its surface is generally rough and perforated with numerous small pores allowing seawater to enter its body.

Its color varies depending on the environment and the presence of symbiotic organisms. It may be brownish-purple, reddish, or sometimes grayish. Its internal structure is composed of a skeleton of siliceous spicules, which gives it a firm and sometimes slightly stony texture.

The stony sponge is found mainly in the Mediterranean sea and in certain areas of the eastern Atlantic ocean, particularly along the European and North African coasts.

The stony sponge usually lives attached to hard substrates, such as rocks or underwater walls. It is most often found in coastal rocky areas, caves, and underwater overhangs, from a few feet to several dozen feet in depth.

It prefers shaded or dimly lit areas, where it can grow sheltered from strong light.

Like most sponges, the stony sponge is a filter-feeding organism. Seawater enters the sponge through numerous small pores and circulates through a network of internal canals.

The stony sponge mainly feeds on microscopic plankton, bacteria, and organic particles suspended in seawater.

This filtration process helps clarify the water and recycle organic matter within the marine ecosystem.

The stony sponge can reproduce in two ways.

The stony sponge is typically hermaphroditic, producing male and female gametes. The sperm cell, released by the sponge, drifts through the water with the currents. If it is drawn into another sponge, it can fertilize an egg. The egg then develops into a free-swimming larva capable of moving through the water using its cilia. It is then expelled from the sponge, before settling on a substrate where it develops into a new sponge.

The stony sponge can also reproduce asexually by fragmentation or budding. A fragment of the sponge detaches, then settles on a substrate and develops into a new individual.

The stony sponge is a favorite food of the dotted sea slug, whose presence is easily recognized by the whitish craters left on the sponge where they have grazed while feeding.