MILAN (AP) — Officials say an ancient ornamental bronze stud has been stolen from an exhibit inside the Pompeii archaeological site.

The 6th century stud was one of four that decorated a reproduction of an ancient door that is part of a special exhibit "Pompeii and the Greeks."

Pompeii's director, archaeologist Massimo Osanna, said Thursday that the stud's removal from beneath an acrylic panel would have taken time to avoid detection by on-site security.

Officials think it was taken during public visiting hours, and police are reviewing video surveillance. The area has been closed to visitors.

The 7.3-centimeter stud belonging to a museum in Basilicata was insured for 300 euros ($333.)

The Pompeii archaeological site preserves the ruins of an ancient Roman town that was destroyed when Mount Vesuvius erupted in A.D. 79.