Prayer nut is a small boxwood orb decorated inside and outside with carving on religious themes. To produce such a prayer nut required considerable skill. Within the scope of the concave were carved miniature stories about the life of Christ and his apostles. The width of a “nut” was no more than 3-5 cm in diameter. To add flavor to patterns were added leaves of spice plants or aromatic oil. Every Prayer Nut is a true work of art. Only the very rich could afford to order such a pocket-like altar. Therefore, possession of “prayer nuts” underlines the high social status. Such orbs were designed to be worn on a rosary or belt and could be used for private devotion when its wealthy owner traveled and are therefore known as rosary beads or prayer nuts. The skill of medieval craftsmen still amazes. Every detail of the composition conceived and executed with maximum precision.
text from: http://vsemart.com/prayer-nut-wood-carving-art/