Hi and welcome to GMB.
Strange one: it could be a stirrup cup (wine glass without a foot) but the bent stem makes me wonder why - perhaps to stop it flopping around when in the stand? It isn't an ornamental bell as there's nowhere to attach the clapper: likewise for a pocket watch stand, unless the photo is deceiving me. Can you confirm that there's nothing protruding from the inside of the bell to tie some thread? Also, if it's rough right in the middle (inside) then that would have been where a little hook broke off.
Other thought is that perhaps it's used as a mini-cloche for gardening, but it is too well finished for that IMHO.