Xestospongia muta, also known as Caribbean barrel sponge or "Redwood of the caribbean", is one of the typical inhabitants of Caribbean reefs. It is found mostly singly or in small groups of two or three sponges at a depth of about 10 meters.
Unfortunately, little is known about the biological basis of this massive and prominent representative of the Caribbean reefs. Little is known about growth, possible age, reproduction and mortality, yet the importance for the ecological system of Caribbean reefs.
The sponge lives in symbiosis with a cyanobacterium called Prochlorococcus marinus "(in the outer layers of the sponge), which gives his brownish-red color.
The tissue of the sponge is hard, almost stony. The surface itself is rough and has sharp, always to the top outgrowth. They are well protected as well as the upper edge is provided with sharp outgrowth too.