Bulla, an amulet worn like a locket, was given to male children in Ancient Rome nine days after birth. Rather similar objects are rare finds from Late Bronze Age Ireland. Roman bullae were enigmatic objects of lead, for the well-off covered in gold foil. A bulla was worn around the neck as a locket to protect against evil spirits and forces. A bulla was made of differing substances depending upon the wealth of the family. Before the age of manhood, Roman boys wore a bulla, a neckchain and round pouch containing protective amulets (usually phallic symbols), and the bulla of an upper-class boy would be made of gold. Other materials included leather and cloth.
A girl child did not wear a bulla, but another kind of amulet, like lunula until the eve of her marriage, when it was removed along with her childhood toys and other things. She would then stop wearing child's clothes and start wearing women's Roman Dress. A boy used to wear a bulla until he became a Roman citizen at the age of 16. His bulla was carefully saved, and on some important 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 the jealousy of men.
Bulla (amulet) Wikipedia
A small number of bullae made of base metal (usually lead, but also tin), or rarely clay, covered with a folded over piece of gold foil, have been found in Ireland dating to the Late Bronze Age. They were presumably worn suspended round the neck with a cord running through the hole below the flat top. The body of the bulla has roughly vertical sides before making a semi-circle or inverted pointed arch at the bottom. The gold is incised with geometrical decoration. The type of object was named for its resemblance to the Roman form. Irish bullae are dated between about 1150 BC - 750 BC. Whether they were purely for adornment or had an amuletic or other function is unclear. Despite the small weight of gold used they would have been only available for elite groups.