Alex Mustard / Grooved brain coral (Diploria labyrinthiformis) at night with polyps extended to feed, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Shane Gross / Elkhorn corals (Acropora palmata) at night silhouetted by a scientist's light during the annual coral spawn. Abaco, Bahamas.

Juergen Freund / Bleached Staghorn corals (Acropora cervicornis), Great Barrier Reef, Australia, 2017.

David Fleetham / Spinyhead blenny (Acanthemblemaria spinosa) in hard coral, Netherlands Antilles, Bonaire, Caribbean.

David Fleetham / Striped triplefin (Helcogramma striata) on hard coral, Tubataha Reef, Philippines.

David Fleetham / Bubble coral shrimp (Vir philippinensis) on Bubble coral (Plerogyra sp), Philippines.

Alex Mustard / Hawksbill turtle (Eretmochelys imbricata) male chomps on soft coral. Jackson Reef, Sinai, Egypt. Strait of Tiran, Red Sea.

Alex Mustard / A stand of Pillar coral (Dendrogyra cylindrus) growing on a coral reef, East End, Grand Cayman, Cayman Islands

Alex Mustard / Boulder brain coral (Colpophyllia natans) photographed with a long exposure with camera rotation. Taken with circular fisheye lens. Grand Cayman, Cayman Islands. Caribbean Sea.

Franco Banfi / Hard and soft corals and encrusting sponge on the structure of bio-rock, Karang Lestari Pemuteran project, Desa Pemuteran, Bali Island, Indonesia, Pacific Ocean

Alex Mustard / Scissortail sergeants (Abudefduf sexfasciatus) swimming over hard corals (Acropora sp.) on shallow reef at sunset, split level view. Gubal Island, Egypt. Red Sea.

Georgette Douwma / Coral line nursery with Acropora corals grown to reintroduce to the Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.