U-Mos is the 5th and probably the last Sentinel of the Luminoth on Aether. He gives Samus Aran the basic information of the crisis of Aether in Metroid Prime 2: Echoes. He also gives her the translator files to read some of the Luminoth text. The sanctuary under his watch, the great temple, preserves the Luminoth in suspended animation. Scans show U-mos has lived for two centicycles (two hundreds years). Whether this is old for a Luminoth or not is unknown.