Lumi

"The mountain knows rage. When it's angry, the snows hurl from its peaks, and crash down in a terrible display. That is why we meditate on Peace."

- Lumi, Mata Nui Online Game II: The Final Chronicle

Lumi was a Ko-Matoran.

Metru Nui
Like most Ko-Matoran, Lumi lived in Ko-Metru, probably working in a Knowledge Tower He was rendered unconscious by Teridax, and placed in a Matoran Pod. He was then rescued by the Toa Metru, and brought to Mata Nui.

Mata Nui
Lumi meditated on Mt. Ihu's anger, as well as Ko-Koro's Principle of Peace on Mata Nui. After the Bohrok War, he was rebuilt by the Turaga into a stronger form.

Return to Metru Nui
When he returned to Metru Nui, he helped to rebuilt the city until the Staff of Artahka was used to repair the rest of it.And is most likely in the Archives now.