This article in the Guardian shows some unusual objects used as bookmarks:
I abhor the practice of turning over the corners of pages to mark where someone left off reading. I also get annoyed when previous readers have left written comments on the page, as I was brought up to value and look after books. I can just about see the point of making useful notes in a textbook, and it’s something that I’ve done with Haynes workshop manuals for cars and motorcycles when I’ve found a better way of doing a repair.
Although I’m able to remember the number of a page, where I left off reading, for, after all, it’s only one number, I tend to use postcards as markers these days—such as when I have four books on the go at the same time. These cards include a greetings card with a charming message from a friend, as well as some American rustic postcards from Wyoming that a photographer sent me. I’ve been known to use squares of tissue paper, though it’s been a while since I had a proper leather bookmark with tassels.
Librarians are always finding bookmarks, and usually, keep a box of them under the counter— just in case a reader asks for their return. When I worked as a librarian, I sometimes found things that we most definitely did not keep. You may find it hard to believe, but these included slices of bacon (cooked and uncooked), condoms (used and unused), combs, straws, razor blades, cocktail sticks, matches and paper-clips. Weirdest of all was a squashed army of woodlice, which I think are known as pillbugs in America. Their flattened corpses marked the reader’s progress through the book. This slaughter had been deliberately done, as the reader left a message declaring her hatred for woodlice beside her last victim!