My friend and I loved to dig in sandboxes a kindergarten (we were 6-7) because we thought we would find valuable treasures someday. Our kindergarten's yard had two sandboxes, and one day, the sand on one of them was 'harder' and more diffucult do dig than usual. I said that the ground was hard because there a was a dinosaur's skeleton under it, we both agreed that it was a good explanation and moved to the other sandbox.
