So I was doing an oil change today, and had left the oil to drain for a while. The drain pan had been left under the oil filter hole thingy for a bit. When I finished the oil change, I poured the old oil off into an old container and found this rubber ring at the bottom. By this time, I'd already put everything back and added new oil. I'm just wondering where this comes from? It doesn't look like part of the old oil filter because it still has it's rubber seal on it. Was this a part of the car?? Have I screwed something up?