The oldest known examples of art to survive from Scotland are carved stone balls, or petrospheres, that date from the late Neolithic era. They are a uniquely Scottish phenomenon, with over 425 known examples. Most are from modern Aberdeenshire, but a handful of examples are known from Iona, Skye, Harris, Uist, Lewis, Arran, Hawick, Wigtownshire and fifteen from Orkney, five of which were found at the Neolithic village of Skara Brae. Many functions have been suggested for these objects, most indicating that they were prestigious and powerful possessions. Their production may have continued into the Iron Age.