A World Essence Crystal

Lin Mu could feel the feel the uneven ground underneath him, but at the same time felt like something was different. 

~step~

And when he took a step, he knew exactly what was different.

"Why is the gravity so weak here?" Lin Mu was confused as he found his body floating after his attest of taking a step.

He looked around and couldn't find anything within the range of his vision or his spirit sense. Picking a random direction, Lin Mu started to walk. 

He ended up walking for about ten minutes before he realized that there was no obstacle in his path.

"Is this a cave? There are no walls that attached to the path up there." Lin Mu muttered in confusion.

His spirit sense could barely touch the ceiling of the underground area but not its borders. It made Lin Mu think that it might really be a large cave since even his spirit sense with a range of nearly hundred kilometer couldn't measure it.