The Dungeon Crab is an insect like reptile, despite it's name as a crab. The only similarities it shares with marine crabs is that it has large segmented legs and moves in a scuttling fashion. They are approximately the size of a medium dog, generally no more than 20 pounds in weight. The crab has four legs, each ending in a tight starburst cluster of claws. These claws are sharp and can dig into rock and wood, and they can move at half speed across vertical and upside down surfaces like the ceiling. They have a very compact head, beady eyes, and a lamprey like mouth.
The individual dungeon crab is a pest. They are thieves, and will steal shiny things, food, and are drawn to open wounds. In larger numbers they become aggressive and will bite and claw at potential food sources with great enthusiasm. The death of a dungeon crab can send the surviving crabs into a frenzy, increasing how fast they attack and how aggressively they will act.
The female dungeon crab has the ability to deliver a poisonous bite. This causes numbness and paralysis. An excessive number of bites can be fatal, but this isn't the intended purpose of the venom. Rather, the female dungeon crab will sedate a foe, and then lay eggs in their bodies while they cannot move. These eggs will hatch inside the host and then eat them from the inside out. If threatened, the female dungeon crab will weaken a foe with her bite to make it easier to bring down and eat.
The Dungeon Crab is a scavenger and cleaner species. They will eat dead creatures, and would be heroes, and will drag their loot to their lairs. Other dungeon dwellers will feed on dungeon crabs, but this isn't a palatable food source, and is akin to eating rats. Dungeon delvers can feed on dungeon crabs, they aren't hard to catch and kill in small numbers, but they do not taste good.
Dire Dungeon Crab - the size of a small person, the dire dungeon crab is a much more bold hunter, and groups of them will move through a dungeon like cowardly wolves. Much larger, stronger, and aggressive.
Zombie Dungeon Crab - a frightening form of undead, the zombie dungeon crab will always go for the head in a desperate attempt to eat the face, and then break into the skull of it's victims to snack on the tenderest of meats. Their bites are very nasty and carry many diseases.
Armored Dungeon Crab - has a much thicker chitinous carapace, much harder to kill. Less aggressive, but much more determined.