This is a prayer nut, or a wooden bead carried in a pocket, purse, or attached to a rosary to aid in prayerful meditation. They were very popular in the northern Europe, and often unfolded into miniature scenes from the Bible. This one dates back to the 16th C. and features the crucifixion, among other things. It is currently on display at the British Museum.
Rosary bead or prayer-nut, boxwood; carved; opening in two halves, upper one closed by two doors. On the outside of the doors, the Virgin in the Temple (left), Marriage of the Virgin (right); inside the same doors, Moses and the Brazen Serpent (left) and the Deposition (right). Inside the upper half of the nut, in deep and delicate relief, the Crucifixion beneath a vaulted roof, staged on several levels.
The lower half of the prayer-nut is shut with one hinged flap which telescopes open, and is carved on both sides: on the front, The Annunciation with the words spoken by the Virgin and by Gabriel within the scene as scrolls; on the other side, The Nativity, with smaller scenes of the Circumcision, Presentation in the Temple and Christ among the doctors. Inside the lower half of the prayer-nut, carved in deep relief is the Bearing of the Cross. On the outside of both halves, Gothic tracery and flower-heads; suspension ring; inscribed.