Claudio Contreras / Giant barrel sponge (Xestospongia muta) Cozumel Reefs National Park, Cozumel Island, Caribbean Sea, Mexico, February

Juergen Freund / Giant barrel sponge (Xestospongia testudinaria) studded with crinoids / featherstars with diver in the background, Kimbe Bay, West New Britain, Papua New Guinea.

Fred Bavendam / Giant Barrel Sponge (Xestospongia testudinaria) spawning, Bali, Indonesia

Jeff Rotman / Diver loooking into Giant netted barrel sponge {Veronguls gigantea} Cayman Islands, Caribbean Model released.

Alex Mustard / School of Bludger trevally (Carangoides gymnosthethus) throng over a coral reef, with a giant barrel sponge (Xestospongia muta). Misool, Raja Ampat, West Papua, Indonesia. Misool Marine Protected Area...

Alex Mustard / West Indian spider crab (Mithrax spinosissimus) shelter in a giant barrel sponge (Xestospongia muta) on a coral reef. Jardines de la Reina, Gardens of the Queen National Park, Cuba. Caribbean Sea.

Magnus Lundgren / Wild Wonders of China / Giant barrel sponge (Xestospongia testudinaria) Xiaoliuqiu Island, Taiwan

Gary Bell/ Oceanwide / Feather Star (Oxycomanthus sp) group on Giant Barrel Sponge (Xestospongia testudinaria) in coral reef, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Feather Star (Oxycomanthus sp) group on Giant Barrel Sponge (Xestospongia testudinaria) in coral reef, Great Barrier Reef, Australia

Alex Mustard / Schools of baitfish including Cardinalfish (Apogon spp) and Silversides (Atherinidae) mass on a coral reef, with Giant barrel sponge (Xestospongia sp.) and predatory coral grouper (Cephalopholis minia...

Alex Mustard / A threadfin hawkfish (Cirrhitichthys aprinus) on a barrel sponge. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Dwarf hawkfish (Cirrhitichthys falco) perched on the ridges of a barrel sponge. Anilao, Batangas, Luzon, Philippines. Verde Island Passages, Tropical West Pacific Ocean.