Pascal Kobeh / Hard coral (Porites lutea) with Christmas-tree worms (Spirobranchus giganteus), New Caledonia, Pacific Ocean.

Alex Mustard / Hard coral reef (Porites sp.) exposed by a low spring tide in front of an island. Yillet Island, Misool, Raja Ampat, West Papua, Indonesia. Ceram Sea. Tropical West Pacific Ocean.

Alex Mustard / Hard coral (Porites sp.) micro-atoll. A microatoll is a circular colony of coral, dead on the top from exposure to air at low tide, but living around the edge. Their presence in coral reef fossils is...

SCOTLAND: The Big Picture / Colourful rocky reef with Dead man's finger (Alcyonium digitatum) and Kelp forest, North Sea, Shetland

SCOTLAND: The Big Picture / Soft coral / Dead man's finger (Alcyonium digitatum) growing on a rocky reef with kelp forest above, Scotland, UK, February.

Linda Pitkin / Stony coral (Porites sp.) with Anthias (Pseudanthias squamipinnis) Ras Ghozlani, Ras Mohammed National Park, Egypt, Red Sea.

Linda Pitkin / Stony coral (Porites sp.) with Anthias (Pseudanthias squamipinnis), and diver Ras Ghozlani, Ras Mohammed National Park, Egypt, Red Sea.

Linda Pitkin / Green finger sponge (Iotrochota birotulata), with colonies of Golden zoanthids (Parazoanthus swiftii), on Netted barrel sponge (Verongula gigantea), on coral reef Klein Bonaire, Bonaire, Leeward Antil...

Alex Mustard / Reef octopus (Octopus cyanea) emerges from its den in a hole in a large hard coral (Porites sp.) at sunset. Sha'ab Mahmood, Sinai, Egypt. Red Sea

Alex Mustard / Hard corals (Porites sp. ) grow in shallow water around limestone rock islands. Korror, Palau, Mirconesia. Tropical west Pacific Ocean

Sue Daly / Deadman's finger soft coral (Alcyonium digitatum) Trondheimsfjord, Norway, July.

Constantinos Petrinos / Giant flathead (Cymbacephalus beauforti) lying on a Finger Leather Coral (Sinularia polydactyla) Lembeh Strait, North Sulawesi, Indonesia.