The Memento Lens can be used to observe statuettes of Earth Kitsunes to reveal hidden things or past events. Statues that can be targeted have glowing Electro markings. Using it can activate mechanisms as well as reveal chests, investigation points, and coded messages.
Using it on Earth Kitsune Statues will typically display the following screen prompt:
Through the Memento Lens, you see something that wasn't there...
Observing an Earth Kitsue Statue with Memento Lens