Jigsaw

Her parents didn't believe her, but there was a monster under her bed. Every night she would scatter the jigsaw puzzles on the floor and the creature would spend the entire dark putting it together, picking up the pieces with its gigantic gnarled hands that were the size of tree trunks, with fingers each as long as a new pencil. It never managed to finish it before morning though, so she was safe. But she kept on buying jigsaws with more and more pieces, just in case.