The magic objects collections in Finnish museums include large amounts of small, roundish, water polished pebbles. These are often called “snake’s court stones” in the local tradition (Fin. käärmeenkäräjäkivet). According to folklore, vipers gathered in the spring to hold a court hearing. They needed to find and punish the viper that had bitten more people than the others. In fact, these kinds of snake’s courts can still be observed in springtime. Nowadays we interpret the gatherings as vipers being awakened from hibernation by the spring sun and crawling out of their shared winter lair.
Folklore tells that during the court the vipers would keep a small pebble in their mouth that circulated from snake to snake. Thus the pebble became “charged” with the power of the vipers. The lucky person who obtained this stone received a magical object that was useful in healing and especially when going to court. When one kept it in the pocket, one would not “tremble”, and thus could be assured that one’s case would be won.
Different snake’s stones are known elsewhere in Europe too (perhaps even beyond?). But the beliefs may vary. If you know variations of this belief, please share it in a comment below!