rubber or plastic?
I've seen worse.
These two pictures are of valve cover gaskets.
The first pic is of a new gasket, fresh out of box.
The 2nd pic is of one that's old and brittle... and leaking.
At least it came out of the cover in one piece. I didn't have to chisel it out.
Hopefully this will take care of my sister Edith's oil leak problems.
Posing in the pictures is Antny, Edith's man.
If you can't see him, click on the pic.