9. Fetus Paper
Before the days of Office Depot, paper was a luxury that was often made from less than savory ingredients. For example, the first collection of portable Bibles in Europe, all 20,000 of them, was said to be printed on parchment made from stillborn barnyard critters.
Known as uterine vellum, or abortivum parchment in Latin, these names suggested that the supremely thin pages came from calf and sheep fetuses. To put the issue to rest, an unexpectedly large collaboration between British, Irish, French, Danish, Belgian, and American scientists devised an innovative way to test the delicate paper without destroying it. They used a rubber eraser.
After a good rubdown, the electrostatic charge elicited from the eraser-on-paper action attracted tiny protein fragments from the pages. Analyzing the meaty dust revealed that the vellum was not, in fact, gruesomely manufactured from aborted animals. Instead, it was made from cows or other hoofed adult animals as per tradition. How medieval artisans were able to create such fine, thin sheets remains a mystery for another day.