In the deserts on mylar’s home world there are many rock towers. Rocks like being on top of each other, it gives them a sense of dominance. So if a rock comes across another rock that has been stuck in the sand it will sit on top of it and not move. They will stay this way for years and as the desert shifts more and more will stack on top. Then once the dunes shift away it reveals a great tower of rocks all too stubborn to move