In describing the cultural significance of stones with holes in them, referred to by many names including hag stones, adder stones, and, in Russian, kurinyi bog. Pliny the Younger said
There is a sort of egg in great repute among the Gauls, of which the Greek writers have made no mention. A vast number of serpents are twisted together in summer, and coiled up in an artificial knot by their saliva and slime; and this is called "the serpent's egg". The druids say that it is tossed in the air with hissings and must be caught in a cloak before it touches the earth (Pliny).
Looking for snakes and looking for adder stones are both deep memories in my childhood. The intersection of where I would look for both of these was the shores of the Grand River and its tributaries. Based on the origin story of the adder stone, and my own memories, I created a bronze pit, writhing around a stone. Stones with holes in them have various mythic properties: protection from poison, revealing secrets, and protecting chickens from predators. My family has a different association with them, though, originating from my grandmother. According to her, if you are travelling and pick up a rock with a hole, you will someday return to the location you found it. I hope that someday this piece will be found, and the adder stone in it, while not real, will cause the finder to return to that place again.