I couldn't find the bone doll (exactly what it sounds like), which previously held the title of creepiest thing in the museum, so I'll finish with this... object.

These dolls are known as 'muñecas de carton de piedra' or 'dolls made of rock paper'. They are made with a technique called cartonerfa, where layers of paper are bonded and moulded with a homemade glue.