The stone structure is a statue of Reptilicus origin, which appears in the Grand Court. It is a bust of a Reptilicus, and a security system presumably put in place by them before they became mad with Phazon Fever. When active, the statue pushes itself along wall-mounted tracks (resembling Spider Ball Tracks), blocking access to a corridor. As it moves, it opens its maw, closing it again when it retracts.
On the first visit to the room in Metroid Prime 3: Corruption, the structure is retracted. Upon jumping down into the main room, the structure pushes forward, obstructing the path to the Hillside Vista. It will not retract until Samus defeats a group of ambushing Reptilicus Hunters. After they are killed, the structure will permanently retract into the wall and become inactive, allowing Samus to reach the Hillside Vista and beyond that, the Grapple Swing.
- "Stone structure is extended and blocking hallway access. Clear hostiles to remove it."
- "Stone structure is retracted into the wall and no longer active. Hallway access granted."