When I was younger, my brother had an aquarium with turtles. It was a fairly large aquarium and he needed some “decoration” to fill it and entertain the turtles. Before Christmas, there were presents under the tree and one with his name on it. It was very heavy, even though it was not that big (maybe 6-8 inches wide and tall). My mom was teasing him by often moving that present, and dropping it, pretending it might have broken. He was so annoyed! It turned out, when he opened it, on Christmas day, that my mom had bought a decorative rock for the aquarium. There was no way it would break, no matter how often she would drop it on our carpeted floor. We had a good laugh for quite a while, remembering how afraid he was to get a broken present!