A bulla (plural, Bullae) is a lump of clay or lead molded around a cord and stamped with a seal that identifies the sender. A boulloterion, an iron, pliers-shaped instrument, was used to impress the designs on a lead bulla seal. After the cord was wrapped around the package or document and the ends inserted in a channel in the blank seal, the seal was placed between the disc shaped engraved dies on the jaws of boulloterion. The boulloterion had a projection above the jaws, which was struck with a hammer to impress the design on the seal and close the channel around the two ends of the cord, securely locking the seal around the package or document. With a bulla in place a container cannot be violated without visible damage to either the bulla or the cord, ensuring the contents remain tamper-proof until they reach their destination.
Bulla, an amulet and worn like a locket, was given to children, at the time of birth, in Ancient Rome. A bulla was worn around the neck as amulet to protect against evil spirits and forces. A bulla was made of differing substances depending upon the wealth of the family. A common substance was leather, but the richer families would have bullae of gold or silver, and poorer families ' would be made of cotton. A girl child continued to wear her bulla until the eve of her marriage, when it was removed and kept along with her childhood toys and other things. A boy used to wear a bulla until he became a Roman citizen. His bulla was carefully saved, and on some special occasions, like his becoming a general and commanding a parade, the bulla was taken out. He would wear the bulla during the ceremony to safeguard against evil forces like jealousy of men.