Petrosia ficiformis, commonly known as the stony sponge, is a petrosiid sea sponge in the order Haplosclerida. Petrosia ficiformis was first described by J.L.M. Poiret as Spongia ficiformers. Its name comes from the Greek: 'pétra' - πέτρα - rock, 'physis' - φύση - nature, 'fórma' - φόρμα - shape, meaning 'naturally-shaped rock'. It is classified under the subgenus Petrosia of the genus Petrosia. It belongs to the family Petrosiidae or the suborder Petrosina. Petrosia ficiformis is found on the underside of rocks, on overhangs and in caves between5 to 70 m (16 to 230 ft) deep.