A crab helmet is a piece of armour. To obtain this item, players must have 15 Crafting and have access to the Mogre Camp, unlocked when players have partially completed Recipe for Disaster and kill crabs until they drop a fresh crab shell, and then use a chisel on it. If successful, the player is granted 32.5 Crafting experience. Failing to do so produces a Broken crab shell. There are no level requirements to wear the crab helmet.
The crab helmet has identical stats to the iron med helm, except the slash defence and stab defence stats are switched.
Subquest of Recipe for Disaster