Bells

From Manners and Customs of the Bible:

It was quite common among ancient nations to have bells hung around the necks of horses, both by way of ornament and to accustom the war-horses to noise. At the present time bells are used in caravans for horses and camels; sometimes being strung around the legs, as well as suspended from the neck. They are designed, not only for ornament, but also to encourage the animals by their sound, to frighten beasts of prey, and to keep the caravan together.
Some suppose that metsilloth, “bells,” were small pieces of metal resembling cymbals, which made a tinkling noise by collision as the horses moved.