Doug Perrine / Diver looking at Purple tube sponge {Aplysina lacunosa} Bahamas, Caribbean

Constantinos Petrinos / Stove Pipe sponge {Aplysina archeri} Bonaire, Caribbean

Sergio Hanquet / Yellow umbrella slug (Tylodina perversa), two feeding on Golden sponge (Aplysina aerophoba). Tenerife, Canary Islands.

Sergio Hanquet / Yellow umbrella slug (Tylodina perversa) on Golden sponge (Aplysina aerophoba). Tenerife, Canary Islands.

Sergio Hanquet / Yellow umbrella slug (Tylodina perversa) feeding on Golden sponge (Aplysina aerophoba). Tenerife, Canary Islands.

Sergio Hanquet / Yellow umbrella slug (Tylodina perversa) on Golden sponge (Aplysina aerophoba). Tenerife, Canary Islands.

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

David Fleetham / Brittle star (Ophiothrix suesonii) on Stove Pipe Sponge (Aplysina archeri). Bonaire, Netherland Antilles, Caribbean.

David Fleetham / Caribbean trumpetfish (Aulostomus maculatus) camouflaged among Tube sponges (Aplysina sp). Bonaire, Netherlands Antilles, Caribbean.

David Fleetham / Scattered pore rope sponge (Aplysina fulva) reproducing by releasing sperm and/or eggs into the water column. Bonaire, Netherlands Antilles, Caribbean.

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.