Stony sponge
Petrosia ficiformis, commonly known as the stony sponge, is a species of petrosiid sea sponge in the order Haplosclerida.
Petrosia ficiformis is usually purple brown in colour due to symbiosis with photosynthetic cyanobacteria, but can be white in the absence of light. It has a compact, hard texture, with spherical oscula irregularly spread over the surface.
Petrosia ficiformis is found on the underside of rocks, on overhangs and in caves between 5 and 70 m (16 and 230 ft) deep.
The species has been described at the following locations: Adriatic Sea, Aegean Sea, Azores, Canaries, Madeira, Cape Verde, Ionian Sea, Levantine Sea, Mediterranean Sea, North Atlantic, Tunisian Plateau/Gulf of Sidra, West Africa, and Western Mediterranean.
