The Decayed Compass of Sato Museum is a 829 years old piece made by Sato Museum, a engineer living in Shanghai.
Considering its age and the quality of the work, people consider it of no value.
It is engraved with asian patterns and some symbols pertaining to Jainism.
This piece doesn't exist, but as a legend. It is said that in the year 1180, Sato Museum, the owner, made use of it in Shanghai to empower the Museum family. Now it is lost, or broken, we will never know.