This is a beautiful antique Tuareg prayer box, known as a Tcherot.  The metal is some sort of silver base-metal mix, and has a lovely antique patina.  The back shows that this piece has clearly been used, and is actually a little rusted (maybe steel?).  The front, however, is in beautiful condition.  

The decorations on the piece are traditional Tuareg etching.  Tcherots such as this one often contain Koranic verses or magical inscriptions that serve to protect the Tuareg from the malevolent power of the desert -- although this one rattles slightly when shaken.  

This Tcherot measures approximately 2 inches x 2 1/2 inches.  The cord measures approximately 30 inches long, and is tied at the back.      

The raised rectangles forms a small pyramid-like structure. On top of the pyramid is a small raised silver mark that symbolizes the "good eye", which is a traditional means of warding off the evil eye.  To counteract the "evil eye", the Tuareg call upon the power of the "good eye," which is represented on this Tcherot by the small sphere in the center.  The spheres around the edges likewise symbolize the four cardinal directions.