Hidden Treasures

Exploration Stage: Postal Dovecote
From: Mr. Black
Description: Assuming the culprit believed he was being watched by me, the pigeons would return here. We can locate the culprit by examining the stolen artifacts. What about this rare artifact?
Completed: Mm. This artifact is a rare artifact from the time of the defenders. I have only seen such an object once before, and that was in a sketch in the archives. The dove must have found this in the fog. There are a lot of unusual things in the fog.