The Red sponge or spirastrella (Spirastrella cunctatrix) is a sponge of the Spirastrellidae family belonging to the demospongiae class. It is an encrusting red-orange sponge (which can sometimes turn green, blue and grey), characterized by very evident channels that culminate in the osculum, rough to the touch due to the presence of spicules. It can also cover large expanses of seabed. It can be confused with the encrusting forms of Crambe crambe. It is common in the Mediterranean Sea up to 30 meters, sometimes present even at greater depths, in dimly lit, rocky environments, often in caves. Often associated with coralligenous and Astroides calycularis.