That was kind of my thought as wellIts possibly a antique book marker, to mark your last page read.
Not... too thick for a book marker.That was kind of my thought as well
Except it would be for keeping the pages from turning.
So once the book was opened it slid between the binding & pages and the long piece would be in the opened page section.
Yeah, it looks like the shape of the back end goes in to a slit/hole and won't pull out.My first thought was 'belt decoration'. From the middle-ages. 13th to 15th C.
I remember seeing something like it on a detecting forum in The Netherlands that I used to frequent, but that was like 10 years ago. I can't find it anymore.