SCOTLAND: The Big Picture / Edible sea urchins (Echinus esculentus) grazing under a kelp forest, Scotland, UK, October.

SCOTLAND: The Big Picture / Edible sea urchin (Echinus esculentus), Shetland Isles, Scotland, UK, MAy.

Sue Daly / Edible sea urchin (Echinus esculentus), Trondheimsfjord, Norway, July.

Sue Daly / Edible sea urchin (Echinus esculentus), Trondheimsfjord, Norway, July.

Sue Daly / White sea urchin (Echinus acutus), Trondheimsfjord, Norway, July.

Sue Daly / Reef wall with Edible sea urchin (Echinus esculentus) and Dead man's fingers soft coral (Alcyonium digitatum), Isle of Man, July.

Sue Daly / Close-up of a Common sea urchin (Echinus esculentus) showing spines and tube feet, Sark, British Channel Islands, UK, 2013.

Sue Daly / Common sea urchin (Echinus esculentus) attached to a wall, with female Cuckoo wrasse (Labrus mixtus) swimming in the background, Sark, British Channel Islands, UK, 2013.

Alex Mustard / A view through Kelp forest (Laminaria hyperborea) with Common sea urchins (Echinus esculentus) grazing on the algae, Farne Islands, Northumberland, UK, North Sea, August

Albert Lleal / Common Sea Urchin (Paracentrotus lividus) in fast moving water showing spines and tube feet, the water penetrates the urchin and provides oxygen, Catalonia, Spain

Albert Lleal / Common Sea Urchin (Paracentrotus lividus) in fast moving water showing spines and tube feet, the water penetrates the urchin and provides oxygen, Catalonia, Spain

Solvin Zankl / Deepsea Sea urchin (Dermechinus horridus) specimen from the Scotia Sea, Southern Atlantic Ocean, near South Georgia Island.