Raninidae is a family of unusual crabs named for their frog-like appearance, taken by most scientists to be quite primitive. These animals closely resemble the (unrelated) mole crabs, due to parallel evolution or convergent evolution. In both groups, the claws are modified into tools for digging, and the body is a rounded shape that is easy to bury in sand. Unlike most other true crabs, the abdomens of raninids are not curled under the cephalothorax. The edible Spanner crab is also part of this family.
In this image, the face of the crab is located on the upper portion.