There are 50 chests scattered throughout the Edania Region, which are called Edana’s Legacy.

Each of the chests can be opened once per family, and each chest will reward you with  Primordial Fragment x1.

Once you collect all 50 chests, you will also earn 2 Max Energy from the Edana’s Legacy Knowledge category.

This video contains every chest in an efficient route.

You can also find each individual chest with screenshots in the BDFoundry guide by clicking on the image below.