The thunderbolt prevents all fiery arrows of a witch. Often when cattle are thriving, someone will envy the cattle-luck. If one does not take precaution, the animals will start to suffer and will not thrive. Old folks used to conceal a thunderbolt under the threshold of the cowshed in the stone foundation, since witches could not cross it. (SKMT IV, 1: I 302 §; Hukantaival 2016: 184)
The international belief that the tip of lightning manifests as a peculiar stone was widely known in Finland up to the 20th century. In this area, these thunderbolts (Fin. ukonvaaja) are most often stones that are now known to be Stone Age polished stone tools, such as axes or chisels. These dark, smooth wedge-shaped stones were seen as very powerful evil-averting objects and medicine.
One could, for example, cure toothache by touching the sore tooth with a thunderbolt or scrape some powder off the stone and mix it with food or drink to give to a patient as medicine for sudden pain. Because of folk medicine uses, archaeological collections are full of Stone Age tools that have been scraped and grinded, heated and chopped.
It was believed that, when lightning struck, the bolt would become buried deep in the ground from the impact. It would then take nine years for the stone to surface. This explained why one could not always easily find the bolt after a thunderstorm and why these stones could be found when digging the ground.