Bursa, or purse-shaped, reliquaries are one of the oldest types of reliquary, with numerous surviving examples from the seventh century onward.

This one, dating from the tenth century, displays a masterful treatment of ivory wherein the surface is modeled by incision and relief carving while the background is pierced through (ajouré).

In the Middle Ages, it was common for ivory-covered reliquaries to display scenes of the life of the saint, whose remains were held within the container, but in this example, the ivory displays more purely decorative imagery.

Source:Bursa Reliquary