Agnus Dei

1) A prayer in the Mass (see Lamb of God).

11kb jpg New Catholic Dictionary illustration of the 'Agnus Dei' (2)
2) A sacramental, consisting of a small piece of wax, blessed by the pope. It is a symbol of the “Lamb of God,” the Saviour. It is usually oval in shape, impressed with the figure of a lamb bearing a banner; on the reverse side is the coat-of-arms of the pope. After being blessed, it is often subdivided into small pieces, and each is enclosed in a leather case. The prayers used by the pope in blessing it show that it is intended as a protection against Satan, sickness, tempests, temptations, and sudden death, and for women expecting motherhood. It is usually worn suspended from the neck, but may be carried in any other manner. No indulgences are attached to it, and there is no obligation to use it. Its history goes back possibly to the 4th century.