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