Ancient Byzantine key, 5th century (Late Antique), bronze.
This type of key, commonly used during the Byzantine period, could be easily carried, an important feature at a time when clothes had no pockets. The hoop of the key fits like a finger ring, and the short barrel can be folded into the palm of the hand. Unlike the teeth on modern keys, the slotted holes on this example are purely decorative, while the small crosses were intended to protect the owner’s possessions.
Источник: Walters Art Museum, USA.