Newspaper clippings inside purport that Christopher Columbus once owned the book, which is said to have been bound with the skin of a Moorish chieftain. It may have passed hands after an era of forcible conversions of Muslim inhabitants to Christianity in Granada, Spain.

But other evidence indicates it may have been in the library of a German book collector around the same time, which contradicts the clippings' timeline. Specifically, an inscription on the title page reads "Sum Christophori Binderi" ("Christophorus Binderus' book"), according to a synopsis from staff curator George Rugg. The university speculates it obtained the book around 1916.

To determine whether it's human skin, scientists use a process that identifies the protein fingerprint of the material. Since other proteins can contaminate the book, the potential human skin piece was taken from underneath the pastedown, an inside area which isn't immediately visible and which is readily reparable. "We tried to be as discreet as possible in taking that sample," Sue Donovan, who is currently working on the project as part of a conservation fellowship, told BuzzFeed.