Cogar,, enlarge the second pic and look at the edge of the circle !! See what you think !! Looks like plywood to me !!
Mart, if that "lid" or "cover" of the internal wiring "connections"
is not a disc of thin metal ...... then it has been "replaced" by an owner of said "hanging lamp".
Now I say that because it is my learned opinion, based on what I see in the above photos, .... it is an art-deco style "hanging lamp" that was produced in a shop or factory
and constructed totally out of metal ...... except for the light bulbs and the insulation on the "AC" lamp cord & plug.
I can see dirt and shadows on that "cover", both pictures, but nothing else out of the ordinary,