Imagery
The Mud Flats of Gungpyeong-ri
This is a more normal crab, mud-colored, making his way slowly across the mud. In fact, I bet he was one of the crabs that picked on Mr. Slow in the previous photo.
The crabs usually travel very slowly, but when a human nears they flash through the shallow water and bury themselves, disappearing in a puff of mud.