Giant barrel sponge

The dominant structure-forming sponge on Caribbean reef walls, sometimes called the 'redwood of the reef' for its longevity — individual barrels may be over 2,000 years old. Giant barrel sponges filter enormous volumes of water, removing bacteria and organic particles and cycling nutrients back into the reef ecosystem. The wall at Punta Izopo is notable for the density and size of its barrel sponge colonies — some exceeding 1.5 m in diameter — which scientists cite as another indicator of undisturbed conditions. Their deep red and purple hues dominate the wall below 15 m.