You marked your place with WHAT?!

AbeBooks reports on some of the odd items that purveyors of used books find inside their wares, many presumably having been used as bookmarks. In addition to a wide variety of currency, these items include rare baseball cards, diamond rings, baby teeth, and a strip of bacon.

As for me, I'm pretty mundane. I typically use the receipt I got when purchasing the book, or a mental note about which chapter/page number I was on.

Hat tip to LIS News.