stone circles and a concentration of carved stone balls. The suggestion is that the stone balls might have been used like ball bearings for transporting big stones. Many of the late Neolithic stone balls have diameters differing by only a millimetre, suggesting that uniform size was important for their purpose. This led to the suggestion that they might have been meant to be used together, or interchangeably. By mapping find-sites in Aberdeenshire, Scotland, it can be shown that often these small stone spheres were found in the vicinity of Neolithic megalithic circles. To test the proposal, experimental archeologists built a model system, substituting hard wooden balls made to the same size. The balls were placed into grooves cut in parallel longitudinal wooden 'sleepers'; these supported an overlying carrying-board that the giant test stone rode on. At least in the situation tested, the model showed such heavy transport to be practical. Platonic solids The carved stone balls have been taken as evidence of knowledge of the five Platonic solids a millennium before Plato described them. Indeed, some of them exhibit the symmetries of Platonic solids, but the extent of this and how much it depends on mathematical understanding is disputed, as configurations resembling the solids can naturally arise when placing knobs around a sphere. There does not appear to be much special attention given to the Platonic solid arrangements over less symmetrical arrangements of knobs over the balls, and some of the five solids do not appear. See also List of prehistoric artworks Brain balls, in Irish archaeology proposed balls made from calcification of enemy's brains Dodecahedra Roman dodecahedron Marble (toy) References Sources External links Archaeological artefact types Prehistoric art Rock art in Europe Ball games Bronze Age Scotland Archaeological sites in Aberdeenshire Neolithic Scotland English sculpture Irish sculpture Scottish sculpture