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At low tide the sand looks more like the lunar surface with lots of large holes and about a foot away from each, a pointed castle of sand.
The crabs are about the diameter of an adult fist and they’re extremely shy on land so hopefully they’re just as shy under water when they see an approaching foot. One needs to look about 30-40 metres ahead to see them and they usually move in groups. Once they see someone they cartwheel towards their hole or skitter to the sea.
Geoff Pound
Image: A sand crab close up (this is not my photo but was presumably taken by a photographer with a telephoto lens) and signs of the sand crab.