Mysterious Black Gasket in Model Y

[Brianhrvey]

So I found this random black rubber thing (about 7" in diameter) on the floor behind the passenger seat of my Model Y after a recent trip.
No clue where it came from or what it's for. Anyone know what this is? Could it be from the car or something else?

 

[SherlockHolmes_67]

Not that I know of any rubber under the passenger seat. Do you have a picture maybe?