Is it glued, or melted into the plastic?
Metal screen or mesh set into a puddle of hot glue.
Zoom in to 200~400%.
I looked for electrical contacts but don't see any. If there was a contact it may have been some sort of ground shield.
The two marks at the top corners appear to be indentations or scratches. The structure is solid, so nothing can pass thru it.
I could never identify it's use from what I can see.
What has been seen can't be unseen :)