The next day I went back to the thrift. It was still there. I bought it.
Turned out it isn't just a bell---it's a rattle. For babies. Hence the inscription "Bebe" on it, which is French for "baby".
Not only is it a rattle, and likely sterling silver, it's Victorian/Edwardian era. Woooo. You don't find much Victorian/Edwardian out in the wild anymore. Most of that stuff gets snared out of the donation piles and goes straight to online auctions and such. So this was a rare and wonderful find indeed!