The populations of Calyx nicaeensis have suffered a great decrease, drastically reducing in several areas of the Mediterranean Sea. This endangered and rare sponge at the present is still not included in any list of protected animal.
A specimen was observed in the August 2008 in the Protected Marine Area of Porto Cesareo (LE) on a coralligenous substrate at a depth of 30 m. This site is characterized by a very rich sponge assemblage where the branched sponge Axinella cannabina is the dominant species.
C. nicaensis shows a particular calyx morphology, sometimes it is characterized by an irregular and massive shape with several extensions thick 1-2 cm. The diameter of the calyx can reach 20 cm. The consistency is hard but fibrous. The colour is variable from beige to dark brown. The skeleton is constituted by a network of tiny siliceous needles (spicules) of two different size: great oxeas (100-150 ìm) and small oxeas (35-80 ìm).
In some site of the Eastern Mediterranean Sea, the sponge is still enough common and the old sponge fishermen use a small piece of the calyx sponge wetted in the sea water like a defogging. It is sufficient scrub the small piece on the glasses of the mask to be sure that during the immersion no fog will form inside it.
Text source: Reef check