Someone putting the rock there on the tree as some kind of marker or boundary is the theory I'll go along with too. My fathers parents owned a farm, and when they had to sell it became a gas station, but an apple tree was left up, as a property boundary. The last time I drove by was years ago, but the tree was still standing. Learning how to think for himself, ask questions and think through the problem... That's how I wish I would have been raised. It's a beautiful day here, 67 and sun-shiny blue skies. It's a Luxury Navy Flake kind of day. Wishes for the best of health to you all!