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The Lower Key is one of two keys found in Blowhole Castle in Wario: Master of Disguise, the other being the Upper Key. It is found in a purple treasure chest in a room in the center of the castle with three Buffy the Dolphins, which is also where the Upper Key is eventually used. An image of the Lower Key is found next to a locked door in the dark room to the left of where the chest is, which is what the key is used to unlock.