Alex Mustard / Yellow tube sponge (Aplysina fistularis) on coral reef, diver exploring in background. Black Rock Drop Off, East End, Grand Cayman, Cayman Islands, British West Indies. Model released.

Jordi Chias / Sponge (Mycale acerata) with diver. Lermaire strait, Antarctic Peninsula, Antarctica.

Franco Banfi / Orange elephant ear sponge (Agelas clathrodes) Santa Lucia, Camaguey, Cuba, Caribbean Sea, Atlantic Ocean

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

Alex Mustard / Yellow tube sponges (Aplysina fistularis) growing on a Caribbean coral reef. Cayman Brac, Cayman Islands. Caribbean Sea.

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 / Portrait of a Giant frogfish (Antennarius commersoni) on a large Yellow elephant ear sponge (Ianthella basta) on a coral reef. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

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

Franco Banfi / Yellow tube sponge (Aplysina fistularis) Dominica, Caribbean Sea, Atlantic Ocean

Nick Hawkins / Finger sponge (Isodictya sp.) growing in the depths off Bonaventure Island, Quebec, Gulf of Saint Lawrence, Canada. September.

Juergen Freund / Marine sponges growing on discarded metal garbage, Sulawesi, Indonesia. November 2018.

Nick Upton / Crumb-of-bread sponge (Hymeniacidon perlevis), orange encrusting form on exposed intertidal rocks. Recent growth pattern visible. Cornwall, England, UK. September.