VATICAN CITY, VATICAN - NOVEMBER 24: Pope Francis blesses relics of St. Peter the apostle, (fragments of bone) for the veneration of believers (for the first time in nearly 2,000 years), during the end of the Solemnity of Christ the King in St. Peter's square on November 24, 2013 in Vatican City, Vatican. (Franco Origlia/Getty Images)

The Vatican on Sunday publicly unveiled a handful of bone fragments purportedly belonging to St. Peter, reviving the scientific debate and tantalizing mystery over whether the relics found in a shoe box truly belong to the first pope.

The nine pieces of bone sat nestled like rings in a jewel box inside a bronze display case on the side of the altar during a Mass commemorating the end of the Vatican’s year-long celebration of the Christian faith. It was the first time they had been exhibited in public. Pope Francis prayed before the fragments at the start of Sunday’s service and then clutched the case in his arms for several minutes after his homily.

No pope has definitively declared that the fragments belong to the Apostle Peter, but Pope Paul VI in 1968 said fragments found in the necropolis under St. Peter’s Basilica were “identified in a way that we can consider convincing.” Some archaeologists dispute the finding.

The relics were discovered during excavations begun under St. Peter’s Basilica in the years after the 1939 death of Pope Pius XI, according to the 2012 book by veteran Vatican correspondent Bruno Bartoloni, “The Ears of the Vatican.”