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.

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

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.

Georgette Douwma / Erect rope sponge (Amphimedon compressa) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stove-pipe sponge (Aplysina archeri) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Erect rope sponge (Amphimedon compressa) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Row pore rope sponge (Aplysina cauliformis) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stove-pipe sponge (Aplysina archeri) and Orange elephant ear sponge (Agelas clathrodes) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Olga Kamenskaya / Diver with Baikal sponges (Lubomirskia baicalensis). Lake Baikal, Russia, March 2007. Model released.