Naming Day was a Matoran holiday in which villagers who performed some great service for their Koro were rewarded with name changes. An exchange of gifts was also customary, although this was more prevalent on Metru Nui than on Mata Nui.
On Naming Days in Metru Nui, ceremonies were held in the Coliseum to honor the achievements of select Matoran. Normally, the public was forbidden from entering Knowledge Towers. The sole exception to this rule took place on Naming Days, when Knowledge Towers opened their astronomical observatories to all citizens so they could have the joy of watching the shooting stars.
Ordinarily, visitors to the Sculpture Fields could take a tour where they got to see the arrival of a block of solid protodermis and watch it be carved into a statue. On Naming Days, Matoran could even get life-size sculptures made of themselves.
Naming Days were held twice a year, at which Matoran who had performed great services were recognized with a new name.
On Mata Nui, when a Matoran performed an exceptionally brave service for his village, he got to attend a special naming ceremony where his name got changed and higher status was conferred on him. Jala was rewarded for his defense of the koro against the Bohrok swarms.
Naming Day ceremonies were held to change the names of Matoran who had performed great deeds.