BULLA. - A lenticular capsule, hollow inside, made up of two superimposed plates and provided with a loop so that it could be worn around the neck. It sometimes also took the form of a heart or a crescent. It was in general use among the Etruscans, who attributed prophylactic virtues to II. The Romans adopted it from them; among the latter it was worn by free-born children and youths, male and female, as those most exposed to the influences of the evil eye and spells. It was made of metal, often precious metal, for the children of patricians, senators, and knights, and of leather for the others. It generally contained objects endowed with special prophylactic virtues. It was laid aside and offered to the household gods at the seventeenth year, when boys assumed the manly toga, and at approximately the same age by girls when they married. The surfaces of the b. were ordinarily smooth, but those of metal were sometimes adorned with repoussé reliefs, usually busts of children or divinities.
The use of bullae also continued among Christians of the first centuries, more from custom than from superstition. They sometimes adorned the front surface with Christian representations, especially the Christological monogram. And it seems that they often placed within them relics of holy martyrs, thus making them true reliquaries, or even small sheets of parchment bearing invocations and adjurations against the powers of darkness.