Try our re-instated info resource - "Aladdin's Cave" (Main menu)- sorry it's taken so long to fix
The shape and the bolt holes look like it may be something off the front footrests. Possibly a home made spacer because the rubber was too big..
Can't help with identifying part, but my ABS (advanced biscuit system) has detected a half used pack of digestive biscuits in that vicinity Don't think they're gingernuts, but then that may be getting too personal