Xestospongia testudinaria is a species of barrel sponge in the Petrosiidae family. It is found in the Philippines, Australia, western and central Indian Ocean, Indonesia, Malaya, and New Caledonia.
This species ranges in size from 3.9 to 7.9 inches in length and 3.9 to 7.9 inches in diameter in intertidal zones. It is maroon to pink, with the opening of the barrel pale white. Specimens are often found emerging from an apparent common base.
Image Caption: Xestospongia testudinaria. Credit: Albert Kok/Wikipedia