The author focuses on explaining the way of using and the function of an iron-and-wood object found during archaeological research of a site at the back of a town plot in the Old Town of Elbląg. The object is dated to the 1240s. A search for analogous archaeological finds in combination with the study of other categories of sources, including ethnographic and iconographic ones, made it possible to establish that this was a tool for cutting grooves in wood. It served to produce long, relatively narrow and not very deep grooves, mainly in shingles.