Autrack

Autrack is a robot from Metroid II: Return of Samus which travels along a track.

The Autrack can be found in numerous Chozo structures on the planet SR388, where it acts as a point defense turret. The autrack is typically found hidden behind a wall or small structure, where it is protected when not firing. When it detects an intruder, its track arm extends, and the cannon fires, once it has fired, the arm retracts while the weapon reloads for another shot.