What’s this item I found in my sewing box?

[PlinkPlankPlunk]

I’m sure it is something for sewing (although I do occasionally put small random things in there for safekeeping.

Its 2cm across and slightly flexible translucent plastic. It has a notch across it so maybe something to do with threading?

Could any sewing MNers save me from throwing it awa6 and regretting it later please?!

Top of a bobbin

It's a bobbin that goes in the bottom bit of a sewing machine.

Ah yes, just the top

Oh, does it detach then from the rest of the bobbin? All my bobbins are solid plastic (this is bendy) but I did throw one away that didn’t have a top! I’ve never seen them like that before (I inherited some sewing stuff from a friend and am just going through it all)

It looks like a seam allowance marker. The one in my pic is metal but you can get plastic ones.

Update - I don’t think it’s bobbin related, as the centre hole is much narrower than a usual bobbin (it doesn’t fit over the one I threw away) unless maybe it’s some sort of buffer that acts like a washer?

I see what you mean about the seam marker @IsDaveThere I’ve never used one as I just use pins and a tape but I’m not sure how easy it would be to use as the notch goes straight across the radius iyswim

i have a feeling I’m going to show it to my husband and he’s going to say oh that that’s the missing bit of the tile cutter/rotary drill/spaghetti maker that I’ve been looking for