Mystery object in my dishwasher

[lastminutelayla]

Help! I’ve found this plastic ring in my dishwasher and I’ve no idea what it’s come from. I can’t think it’s come from anything washed in there, so maybe it’s something from the dishwasher itself which needs to go back from whence it came. It’s a Bosch dishwasher, new last year.
Does anyone have any ideas?
(Sorry for the boring thread but I could really do without my dishwasher packing in over Christmas! Got family staying!)
Picture shows the plastic rubbery ring. Teaspoon is for scale. It’s not the teaspoon I’m worried about!

Is it from a reusable water bottle?

Looks like the seal that sits inside a Tupperware lid

Has it come off the bottom of a plastic bowl or plate?

I did wash a Tupperware pot but it doesn’t fit, and I’ve checked another one in the same style that I have and it doesn’t have the rubber ring. I’m worried it’s a seal for some part of the dishwasher but I’ve investigated the filter bits and there’s nowhere it seems to fit.

Is it from travel mug? It looks exactly like mine

Mystery solved! It’s from DD’s festive tumbler with a straw inside thing. Just looked at DS’s one and it has the same ring. Thanks all!

Have you topped up the salt recently? It's not identical, but my old Bosch did have a white, plastic ring between the screw in part and the filter plate/cover for the salt reservoir.

I wondered if it would be that. I found exactly the same thing in my dishwasher once. It had to be from the machine itself, though I never worked out where. Machine still going strong without it a couple of years later.

X posted. Ignore me.