Sentinel

Sentinels are serpentine robotic enemies in Metroid Prime: Federation Force. They are encountered during the battle against Cyranon, a lava-dwelling machine. They serve as a diversion tactic for Cyranon, with their attacks consisting of fireballs and rocks spewed from their mouths at the Federation Force. They can be defeated, but will return for the second phase of the battle. The Sentinels are gone for the third phase, however.