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

Franco Banfi / Elephant ear sponge (Ianthella basta) with a scuba diver swimming in he background, Gorgonia Wall Reef, Cabilao Island, Bohol, Central Visayas, Philippines, Pacific Ocean.

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

Tony Wu / Yellow elephant ear sponge (Ianthella basta) with unique lighting to make it resemble a sculpture, Hornbill Channel in Milne Bay, Papua New Guinea.

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

Franco Banfi / Red fan corals (Paramuricea clavata), Yellow gorgonian, (Eunicella cavolini) and Yellow cave-sponges (Aplysina cavernicola), Ischia Island, Italy, Tyrrhenian Sea, Mediterranean.

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

Claudio Contreras / Row pore rope sponge (Aplysina cauliformis) Cozumel Reefs National Park, Cozumel Island, Caribbean Sea, Mexico, February

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

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