This relic is found in the DAIRY PLANT and can only be collected once.
When:
Reach level 20 in the Mad Forest to unlock the Inlaid Library.
Reach level 40 in the Inlaid Library to unlock the Dairy Plant.
Method:
On the screen you'll see a green arrow pointing to the south. Follow this arrow for some time until you reach the relic. You'll unlock an in game map.