What is this rubber bung/component on my Mk1 chassis?

Hi,
Please could somebody tell me what this is on my Mk1:

In so much as I could feel, and looking at the photo it looks akin to the top of a suspension mounting, except it’s facing down from the chassis, and doesn’t appear to match with anything I could see in the boot.

Reason I’m asking is the metal above the rubber has rusted and there’s a strip of metal/rubber peeling away from the car which is sort-of visible in the picture on the outer left of the circled area. I wondered if maybe it was some form of bump stop (or at least something cheap to repair)?

Oh, and in case it helps, this photo was taken from the passenger side, pointing the camera towards the suspension area.

Thanks :slight_smile:

It’s part of the diff mounting bush called the stop washer, there’s one each side. I’ve recently replaced mine when I rebuilt the suspension, MX 5 parts stock them

Thanks for the reply :slight_smile: