It is a reflection...
One of the reasons I posted that particular picture is I thought it played with your perspective. I took it through a glass window... if you look very carefully you can see a reflection of one of the PR posters on the wall, along with the words 'James Webb'.
The silvery orb is the reflection of a light in the room behind me... the 'sky' is the far wall of the cleanroom...
I am not sure what the survey instrumentation is for...
The mirrors are covered with black shields to protect them since they are facing upwards... you don't want a dropped tool banging into them!