It was basically the same idea as the small crystal used in the ancient earth during the apocalypse to determine when an alien was near.
The light in the crystal would also change when someone holding it got close to aliens even if they had transformed themselves into human appearance.
"Alright then. Tomorrow, we can take a team to go out and test the efficiency of this device. Let's see how many aliens it will detect during our fishing trip and hunt." Leng Pan happily took the disk and examined it with a smile.
Her little brother-in-law was really accomplished.
If they had such help early on in the apocalypse in ancient earth, maybe they wouldn't have been defeated and have to destroy the world just to eliminate as many aliens as possible.
Leng Pan held the small metal disk between her fingers, turning it over slowly as she examined its structure.
At first glance, it looked like a simple disk or compass.
