Sulpher Sponge
Cliona celata

f22 @ 1/60s, ASA 25, Kodachrome 25 slide film, Nikonos II w 28mm and 1:2 extension tube, Oceanic flash with aluminum flash reflector

"Cliona celata," Wikipedia, the free encyclopedia. Occasionally called the Red Boring Sponge, is a species of demosponge belonging the family Clionaidae. It is found worldwide. This sponge creates round holes up to 5 cm in diameter in limestone or the shells of molluscs, especially oysters. The sponge itself is often visible as a rather featureless yellow or orange lump at the bottom of the hole. These sponges are common in Southern New England and in Narragansett Bay. They also live in the Bahamas, and the western Atlantic Ocean. They usually live in lagoons or on reefs. They will sometimes make their home on dead mollusks or other shelled creatures.
Ft. Wetherill, Narragansett Bay, Narragansett, Rhode Island