Early on, modern households on the shores of Lake Constance were home to unusual objects. Objects that were not common in other houses: strangely shaped stones with smoothly polished surfaces were used to weigh down piles of laundry. The smaller specimens were used as so-called thunderbolts: carried in your pocket, they had a magical effect and protected against back pain. Placed under the roof of the house, they prevented lightning strikes. According to legend, they were thrown down by Thor, the thunder god, during a thunderstorm and got stuck in the lake. When the water level was low, it was easy to collect them. Stone fragments from the flintstone islands near Wallhausen and Nussdorf were also a popular collector’s item.

Stone fragments from the flintstone islands near Wallhausen and Nussdorf were also a popular collector’s item. They were even offered for sale. Nobody could explain how these stones, which do not occur naturally here, got into the lake, but together with a steel striker and tinder, they were useful for making fires. At least until the invention of the match in 1820. For a long time, they served as flints in flintlock rifles to provide the necessary spark.