Borojevia cerebrum

Borojevia cerebrum is a calcareous sponge species found in the Mediterranean Sea. It is distinguished by its brain-like appearance, although the fragmented nature of the holotype makes it difficult to determine its full organization. The sponge features thin-walled tubes composed of a meshwork of spicules, including triactines, tetractines, and tripods. Triactines are the most abundant, with conical or cylindrical actines, while tetractines have conical actines with sharp, straight apical actines adorned with spines. The apical actine of the tetractines is thinner and shorter than the facial ones, with sharp spines arranged in rows pointing towards the tip. Tripods are less common and located on the surface of external tubes, characterized by stout, conical actines with sharp tips.