I just finished changing the oil in my 08 Honda Element. I went in from the top back of the engine to replace the oil filter. When I was finished and I pulled the cardboard out from under my car, there was a little rubber stopper on there. It is about 1 inch long and about 1 inch wide at the top and it tapers down to about 1/2 inch at the bottom. It has a little rounded nob on top. I might have knocked it loose while trying to get to the oil filter. Anyone know what this could be? To add insult to injury and can’t find where I put it right now or I would take a picture it.