You wouldn't want to pull this crab up in your pot!
The Ucides Cordatus, a stunning purple and green colored species of Mangrove Crab found in South America, this crab doesn't live under water. Choosing to inhabit the tidal mangrove areas and feeding on leaves from the trees above, these little guys burrow underground when high tide comes, sealing their burrows to be airtight and emerging again as the tide falls. They're apparently pretty tasty too, considered by many to be superior in eating to mud crabs.
Have you ever had a crab try to attack you when fishing? It's not the first time a crab has been snapped wielding a knife, so if you have any pics or footage, show the community in the General Forums!