An expensive tiny object

But he was certain that he didn't see any monster there just now before he went out of the passage.

…Could it be… this monster could camouflage itself like an armadillo?

Adam could do the same thing. But his ability was not just as simple as camouflaged. He could enter a sub-space to hide and become completely invisible while he was there.

That was the work of mana.

Mana was truly a mysterious energy. Aside from calling it mana, researchers and all geniuses in Science, Technology, and Astronomy, called that thing 4d Energy.

It was called 4d Energy because of the things mana could do, create, or produce, which was supposedly not possible in a 3-dimensional world.

In that sense, mana was beyond a 3-dimensional world. So in conclusion, it was a thing that was only possible in a 4-dimensional world, therefore, it wasn't wrong to call it 4d energy.