David Fleetham / Colony of Green tube coral (Tubastraea micranthus) feeding at night, Fiji Islands.

Georgette Douwma / Black tree coral (Tubastrea micranthus) and Dendrophylliida growing on a large granite boulder. Andaman Sea, Thailand.

Georgette Douwma / Black Tree Coral (Tubastrea micranthus), Dendrophylliida growing on a large granite boulder. Andaman Sea, Thailand.

Pascal Kobeh / Plastic bag hung on a branch of hard corals green cup corals (Tubastrea micrantha). Plastic bags such as this can easily be mistaken for jellyfish by turtles. Mafia Island, Tanzania, Indian Ocean.

Pete Oxford / Black Sun Coral (Tubastraea micranthus) and Sea Goldie (Pseudanthias squamipinnis) school, Fiji

Franco Banfi / Polyp detail of coral (Tubastraea micrantha) Maldives, Indian Ocean

Juergen Freund / Gorgonian fan and black tree coral (Tubastrea micrantha) on coral reef, Moluccas Islands, Indonesia

GEORGETTE DOUWMA / Black Tree Coral (Tubastrea micranthus), Dendrophylliidae, with Klein's Butterflyfish (Chaetodon kleinii). Indonesia, October.

GEORGETTE DOUWMA / Black Tree Coral (Tubastrea micranthus), Dendrophylliidae. Indonesia, October.

Pascal Kobeh / Coral formation with invertebrates and among them feather stars / crinoids and Green cup corals (Tubastrea micrantha) Indonesia, Sea of Flores.