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.

Juergen Freund / Tube corals {Tubastrea faulkneri} with polyps open, Indo-Pacific

Doug Perrine / Orange cup coral feeding {Tubastraea coccinea}

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

Jeff Rotman / Cup coral {Tubastrea sp} feeding on Silverside fish at night, Red Sea

Alex Mustard / Large green branching coral (Tubastrea sp.) with damselfish on a coral reef. Misool, Raja Ampat, West Papua, Indonesia. Misool Marine Protected Area. Ceram Sea. Tropical West Pacific Ocean.

Doug Perrine / Sea slug (Nembrotha cristata) with crest, crawling amongst Sun coral (Tubastraea sp). Puerto Galera, Mindoro Island, Philippines.

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