It wasn't the ground.

Gao Yang felt disheartened; they were still underground, facing a massive subterranean space.

By his estimation, it was at least as large as three sports fields. In the center of the space grew a towering tree, its branches lush yet leafless.

The colossal tree shimmered with a sacred and lonely white light. Upon closer inspection, it wasn't light but white energy hidden within the semi-transparent trunk, flowing silently like the tree's lifeblood.