A mesh-covered hollow roll placed on top of a Fourdrinier papermaking machine. The dandy roll breaks up fibre clumps to improve sheet formation and can also create watermarks in paper, by pressing onto newly formed fibres. If the roll has been produced with raised elements, those elements press into the fibres leaving an impression which, when the paper is formed, allows more light to be seen relative to the thicker background paper. This is a form of watermark, albeit only 2D.