Bibliophage

This cannibalistic book hides deep in the bowels of ancient libraries, eating ruined or decaying books. Though many scholars hate these creatures for potentially destroying priceless historical documents, these creatures actually help keep the library's "ecosystem" in balance by removing moldy or ruined materials. The Bibliophage becomes stronger the more material it eats and can even become bold enough to attack passing adventurers if they appear to be carrying tasty reading materials.