So, let's talk about what books, bats, and Portugal have in common. Portugal has two libraries in Mafra and Coimbra, hosting historical texts from the 15th century onwards.
Now imagine those pages that you'd probably love to check out. And who else do you think is curious? Bugs. They love chewing the pages out.
So, someone needs to come to the rescue, and that's Bats. Not Batman, but the actual bats. Close to The Joanina Library in Coimbra, they have their nest in the gardens. They come at night and hunt for the bugs in the library. Then they return home peacefully.
They are welcome to roam. However, before nightfall, the 18th-century tables inside are covered in fabric to keep the place clean. After the bat dinner, the tables are uncovered for human visitors.