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.

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

Alex Mustard / A diver exploring a coral reef with formation of brown tube sponges (Agelas conifera) red rope sponges (Amphimedon compressa) and deepwater sea fans (Iciligorgia nodulifera) East End, Grand Cayman, Ca...

Juergen Freund / Orange cup coral (Tubastrea faulkneri) with polyps open, Batangas, Philippines.

Juergen Freund / Orange cup coral (Tubastrea faulkneri) detail of mouth and tentacles, Batangas, Philippines.

Norbert Wu / Orange Tube Coral (Tubastraea aurea) polyps extended only at night, Dutch Antilles, Caribbean

Georgette Douwma / Tube coral polyps feeding {Tubastrea faulkneri} Milne Bay, Papua New Guinea

Magnus Lundgren / Wild Wonders of China / Yellow tube coral (Tubastrea faulkneri) with the polyps open, Ninepin Group or Kwo Chau Islands, Hong Kong, China.

Magnus Lundgren / Wild Wonders of China / Sun / Tube coral (Tubastraea sp) with tentacles extended to catch zooplankton. Gulf of Bohai, Yellow Sea. Penglai / Dengzhou / Tengchow, Yantai, Shandong Province, China.

Magnus Lundgren / Wild Wonders of China / Sun / Tube coral (Tubastraea sp) with tentacles extended to catch zooplankton. Gulf of Bohai, Yellow Sea. Penglai / Dengzhou / Tengchow, Yantai, Shandong Province, China.

Linda Pitkin / Orange cup coral (Tubastraea sp.), and soft corals, Triton Bay, near Kaimana, West Papua, Indonesia

Linda Pitkin / Orange cup corals (Tubastraea sp.), Triton Bay, near Kaimana, West Papua, Indonesia

Franco Banfi / Orange cup coral (Tubastrea coccinea) Malpelo Island National Park, UNESCO World Heritage Site, Colombia, East Pacific Ocean

Franco Banfi / Polyp of Orange cup coral (Tubastrea coccinea) Malpelo Island National Park, UNESCO World Heritage Site, Colombia, East Pacific Ocean

Georgette Douwma / Coral reef scenery with Orange elephant ear sponges (Agelas clathrodes), Stove-pipe sponge (Aplysina archeri) and Boulder brain coral (Colpophyllia natans) Bonaire, Netherlands Antilles, Caribbean, A...

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

Georgette Douwma / Coral reef scenery with Orange elephant ear sponge (Agelas clathrodes), Stove-pipe sponge (Aplysina archeri) and Azure vase sponge (Callyspongia plicifera) Bonaire, Netherlands Antilles, Caribbean, A...

Pascal Kobeh / Close-up of the polyps out of a coral tree (Tubastraea coccinea) at night, Baja California peninsula, Mexico. Sea of Cortez.

Alex Mustard / Roughhead blenny (Acanthemblemaria aspera) high magnification portrait of a golden variety of living in it's tube on a coral reef, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbea...

Jeff Rotman / Tube / Orange Sun Corals (Tubastrea faulkneri), also known as Orange Sun Corals, polyps open to feed at night. Egypt, Red Sea.

Juergen Freund / Orange cup coral (Tubastrea faulkneri) Batangas, Philippines.

Juergen Freund / Split-level shot of Tube corals (Tubastrea sp) encrusted on mangrove roots in the shallows. North Raja Ampat, West Papua, Indonesia, February 2010.

Juergen Freund / Yellow cup coral (Tubastraea faulkneri), which opens at night. Misool, Raja Ampat, West Papua, Indonesia.

Juergen Freund / Tube corals (Tubastrea sp) encrusted on mangrove roots in the shallows. North Raja Ampat, West Papua, Indonesia, February.

GEORGETTE DOUWMA / Coral polyps of Tube coral (Tubastrea faulkneri), Milne Bay, New Guinea, Indo-Pacific

Constantinos Petrinos / Christmas tree worm {Spirobranchus giganteus} amongst Orange cup coral {Tubastrea coccinea} Bonaire, Caribbean

Constantinos Petrinos / Orange cup coral {Tubastrea coccinea} and Tube sponge, Bonaire, Caribbean

Constantinos Petrinos / Orange cup coral (Tube coral) polyps (Tubastraea genus) Sulawesi, Indonesia

Constantinos Petrinos / Christmas tree worm (Spirobranchus giganteus) amongst Orange cup corals (Tubastrea coccinea) Bonaire, Caribbean

Peter Scoones / Hard coral with polyps open {Tubastrea sp} Red Sea, Egypt

Juergen Freund / Tube coral, polyps open {Tubastraea sp} Indo Pacific

Constantinos Petrinos / Orange Cup corals {Tubastrea coccinea} & Tube sponge. Bonaire, Caribbean

Solvin Zankl / Orange cup coral, polyps open {Tubastraea coccinea} Virgin Is, Caribbean

Jeff Rotman / Cup coral polyps {Tubastraea sp} feeding at night Red Sea

David Fleetham / Close up of a tube coral (Tubastraea faulkneri) polyp with tentacles extended, taken at night, Indonesia.

Georgette Douwma / Orange cup coral (Tubastrea sp.) Cebu, Malapascua, Philippines, September

Peter Scoones / Hard coral with polyps open {Tubastrea sp} Red sea

Peter Scoones / Hard coral with polyps open {Tubastrea sp} Red sea

Alex Mustard / Coral grouper (Cephalopholis miniata) resting in its green coral (Tubastraea sp.) home, Raja Ampat, West Papua, Ceram Sea, Pacific Ocean.

Alex Mustard / Reef scene with Orange elephant ear sponge (Agelas clathrodes), Brown tube sponges (Agelas conifera), Deepwater sea fans (Iciligorgia nodulifera), Creole wrasses (Clepticus parrae) and Fairy basslets...

David Fleetham / Orange cup coral (Tubastraea coccinea) polyps on coral reef, Hawaii, Pacific Ocean.

Franco Banfi / Orange cup coral (Tubastraea coccinea) and Sea fans (Muricea appressa) covering rock face, Espiritu Santo Island, Baja California, Mexico, Sea of Cortez.

Claudio Contreras / Cortez damselfish (Stegastes rectifraenum), Mexican Hogfish (Bodianus diplotaenia) juvenile and Orange Cup Coral (Sea of Cortez), Mexico, August

Claudio Contreras / Gorgonian and orange cup coral (Tubastraea coccinea) inside cave, San Diego Island, Islands of the Gulf of California Protected Area, Gulf of California (Sea of Cortez), Mexico, September

Claudio Contreras / Pacific mutton hamlet (Alphestes immaculatus) and Orange Cup Coral (Tubastraea coccinea), San Diego Island, Islands of the Gulf of California Protected Area, Gulf of California

David Fleetham / Dead colony of Orange cup coral (Tubastraea coccinea), only the white calcareous skeleton remaining, possibly predated on by nudibranch (Phestilla melanobrachia), Hawaii.

David Fleetham / Orange cup coral (Tubastraea coccinea) close up, Philippines.