The Laurentian Library houses about 11,000 manuscripts, 2,500 papyri, 43 ostraca, 566 incunabula, 1,681 16th-century prints, and 126,527 prints of the 17th to 20th centuries. The core collection consists of about 3,000 manuscripts, indexed by Giovanni Rondinelli and Baccio Valori in 1589, which were placed on parapets ("plutei") at the library's opening in 1571. These manuscripts have the signature "Pluteus" or "Pluteo" ("Plut."). These manuscripts include the library the Medici collected during the 15th century, which were re-acquired by Giovanni di Medici (Pope Leo X) in 1508 and moved to Florence in the 1520s by Giulio di Giuliano de' Medici (Pope Clement VII). The Medici library was joined by collections by Francesco Sassetti and Francesco Filelfo and manuscripts acquired by Leo X and by the library of the Dominican convent of San Marco.