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Monkey corpses are what is left after killing a level 3 monkey (AKA: Karamjan monkey). Until recently the monkey had to be killed with ranged, magic, or a halberd, now it can be killed with any weapon to retrieve a corpse. If a player attempts to use a knife on it before starting the below quests, they will receive a message saying: "You don't know how to skin a monkey...yet."
During Tai Bwo Wannai Trio, it is used to get Monkey skin. During Monkey Madness and later on, it can be used to make Monkey greegrees. When seaweed is used on it, it becomes a stuffed monkey.