Hi All,
I have a shower stall in my master bath. The drain grate was loose, so I unscrewed it to investigate.
The drain grate is round (4 and a quarter inches measured left to right) and uses two screws to attach to a black rubber gasket.
The rubber gasket has a hole on one side where one of the screws fits into. The other side of the gasket no longer has a receptor for the 2nd screw; it has disintegrated over the years. The gasket is also cracked from age in a few places. My house is 10 years old and so is this plumbing.

Just beneath the gasket I can see threads the next piece of drain, which seems obvious that the gasket screws onto that next piece.
It would appear to me that if I can remove the black gasket, I can find a replacement part and make an easy repair for both the gasket and the loose grate.

I'm confident the gasket can be removed because of the threads on the other piece of drain just below the gasket. I've tried to remove the gasket. Its in there pretty securely and I'm afraid to damage the (plastic or fiberglass) shower enclosure. I don't want to remove the gasket through severe means if it isn't meant to be removed!

Is the gasket meant to be removed?
If so, how can I remove it?
I've searched a few sites on the internet, and this gasket method for a shower stall drain doesn't seem too popular. Would it be difficult to find a replacement gasket? (is there a better plumbing term for this part?)

thanks much-