[Updated: There are now pictures of both top and side views. Scroll to bottom of post to see the side views.]
While sorting through family artifacts, I found a black metal two-layer disc with a long spindle. One layer (marked "This Side Up") was about 5 1/2 inches in diameter; the other about 4 1/2". The smaller disc had an inside ring with what appears to be lettering or symbols. See photos (four in all) for various views.
What is the object?