I have a theory about rocks. I believe they can move from one place to another on their own. How else can you explain the appearance of stones where none existed before? Squirrels don't carry and bury stones like they do bulbs and acorns. I believe the rocks move when they know we are not looking.
I love them and began keeping a rock collection as a child. I remember finding the perfectly hamburger shaped stone that I kept in a box in the basement, the square box of a rock