The Earth Maze is not like regular ancient ruins where specific building materials form the main passages; here, the passages seem as if ancient humans used tools to carve them little by little out of the massive rocks.
If it weren't for the high integrity of these rocks, Feng Yuan might suspect whether the Earth Maze is actually an ancient ruin or just a facility modified and used by the academy.
Such enormous and intact rocks do not exist in nature because Spirit Beasts use Ultimate Moves to influence the surrounding environment, coupled with geological movements and other factors, making it impossible for rocks of such size to remain as intact and seamless as they appear now. If the rocks had many cracks, Feng Yuan would believe it's quite possible they exist naturally.
As for this one?
