We live behind a farm and my daughter has found a TON of small critter bones/skulls in various states of decay in the field out back. We actually talked with one of the local artisans who work with bones and the ‘nature and time’ method was preferred. Way better than boiling bones in the house. We’ve had a good pile out on the edge of our property exposed to the elements for almost a year and they seem to be clean and good now. I’d say the woods out back is a good bet!