A stone demon statue and a cave

Spoilers! For those who don't want to discover details of the plot and world, don't read any further!

Finished the quest with the anomaly in Rito's village and returned to the sentry fort and found a hole in the wall of the refuge that the cleaner had made. Inside was found a stone statue. He took my heart. Then returned it at my request.
Who knows if the exchange with him affects anything further in the story? What options are there.

And the cave behind this hole. It's just huge! Reached the room in which in the center lies a large pile of stones. Beneath it, by all appearances, are the bones of Stalnox. How far into this cave does it go, and is there anything interesting there?