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.

Alex Mustard / Yellow tube sponge (Aplysina fistularis) on a coral reef, with the camera rotated during the long exposure. East End, Grand Cayman, Cayman Islands. British West Indies. Caribbean Sea.

Alex Mustard / Spotlight goby (Gobiosoma louisae) looking out from inside a Yellow tube sponge (Aplysina fistularis), growing on a coral reef. Bloody Bay Wall, Little Cayman, Cayman Islands, British West Indies. Car...

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

Alex Mustard / Yellow tube sponge (Aplysina fistularis) top view of tubes with water swirling around them, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Jeff Rotman / Yellow tube sponge (Aplysina fistularis) Red Sea, Egypt

Doug Perrine / Yellow tube sponge {Aplysina fistularis} with Yellowtail snappers {Ocyurus chrysurus Cayman Brac, Cayman Islands, Caribbean

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

Franco Banfi / Spotted moray eel (Gymnothorax moringa) inside Yellow tube sponges (Aplysina fistularis) Dominica, Caribbean Sea, Atlantic Ocean.

Pete Oxford / Yellow tube sponge (Aplysina fistularis) Lighthouse Reef Atoll, Belize Barrier Reef, the second largest barrier reef system in the world. Belize.

Claudio Contreras / Yellow tube sponge (Aplysina fistularis) Cozumel Reefs National Park, Cozumel Island, Caribbean Sea, Mexico, January

Claudio Contreras / Yellow tube sponge (Aplysina fistularis) Cozumel Reefs National Park, Cozumel Island, Caribbean Sea, Mexico, February

Michael Pitts / Tube or trumpet sponges (Aplysina fistularis?) Tobago. Caribbean

Alex Mustard / Diver photographing a large formation of yellow tube sponges (Aplysina fistularis) growing on a coral reef, North Wall, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea. Model released...

Alex Mustard / Yellow tube sponge (Aplysina fistularis) selectively illuminated with a diver swimming above, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / Yellow tube sponge (Aplysina fistularis) on a coral reef, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Pete Oxford / Yellow tube sponge (Aplysina fistularis) on coral reef, Coral Reef Island, Belize Barrier Reef, Belize

Pete Oxford / Yellow tube sponge (Aplysina fistularis) on coral reef, Coral Reef Island, Belize Barrier Reef, Belize

Pete Oxford / Yellow Tube Sponge (Aplysina fistularis) group, Xcalak National Reef Park, Mahahual, Quintana Roo, Mexico

Doug Perrine / Caribbean trumpetfish, Caribbean {Aulostomus maculatus} hiding amongst tube sponge {Aplysina fistularis} Dominica, Caribbean

Juergen Freund / Yellow tube sponge {Aplysina fistularis} growing on shipwreck, with diver in background, Caribbean

Juergen Freund / Yellow tube sponge and diver (Aplysina fistularis) Caribbean

Juergen Freund / Yellow tube sponge (Aplysina fistularis) Caribbean

Jurgen Freund / Diver swimming over Yellow tube sponge (Aplysina fistularis) Caribbean

Doug Perrine / Yellow tube sponge {Aplysina fistularis} and Sea fan coral {Gorgonia ventalina} Cayman Islands, Caribbean

Doug Perrine / Diver and Yellow tube sponge {Aplysina fistularis} Virgin Islands, Caribbean

Doug Perrine / Divers and Yellow tube sponge {Aplysina fistularis} Virgin Islands, Caribbean

Juergen Freund / Yellow tube sponge and diver (Aplysina fistularis) Caribbean

Juergen Freund / Diver and Yellow tube sponge (Aplysina fistularis) growing on ship wreck

Pete Oxford / Yellow Tube Sponge (Aplysina fistularis), Lighthouse Reef, Belize

Roberto Rinaldi / Yellow tube sponges (Aplysina fistularis), Belize.

Roberto Rinaldi / Yellowtail snapper (Ocyurus chrysurus) in front of Yellow tube sponges (Aplysina fistularis), Belize

Roberto Rinaldi / Yellow tube sponge (Aplysina fistularis), Sulawesi, Indonesia.

Roberto Rinaldi / A scuba diver shining his torch on big Yellow tube sponges (Aplysina fistularis), Belize

Roberto Rinaldi / A typical Caribbean reef scene with small colourful fish in front of big Yellow tube sponges (Aplysina fistularis) and a shoal of jacks (Carangidae) swimming above, Belize

Roberto Rinaldi / A shoal of jacks (Carangidae) swimming over some big Yellow tube sponges (Aplysina fistularis), Belize

Roberto Rinaldi / Yellow tube sponge (Aplysina fistularis), Sulawesi, Indonesia.

Roberto Rinaldi / Big Yellow tube sponges (Aplysina fistularis) on a Caribbean reef, Belize

Juergen Freund / Yellow tube sponge {Aplysina fistularis} Snapper fish. Caribbean

Alex Mustard / Yellow tube sponge (Aplysina fistularis) portrait, Grand Cayman, Cayman Islands, Caribbean Sea.

Alex Mustard / Scuba diver exploring the Kittiwake shipwreck, with dense growth of colourful sponges including Branching tube sponge (Pseudoceratina crassa) and Yellow tube sponge (Aplysina fistularis),Seven Mile Be...

Alex Mustard / A yellow tube sponge (Aplysina fistularis) growing on a Caribbean coral reef, withsun burst above. East End, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Claudio Contreras / Yellow tube sponge (Aplysina fistularis) and diver, Guanahacabibes Peninsula National Park, Pinar del Rio Province, western Cuba., Floating debris cleaned