Spider Ball Track

Spider Ball Tracks (also referred to as magnetic rail system tracks) were introduced in Metroid Prime and since then have appeared throughout the Prime Trilogy. They can only be traversed once the Spider Ball is acquired. Holding down R (in the Gamecube versions) or Z (in the Wii versions) near a magnetic rail will stick the Morph Ball it like a spider. Moving the control stick will move the Morph Ball along the tracks, which often lead to hidden places. In Metroid Prime 2: Echoes and Metroid Prime 3: Corruption the Boost Ball will repel Samus away from the track and Bombs will send Samus up.

Magnetic rails are often used by the Space Pirates for transport of small cargo, perhaps by small drones. A Spider Ball Track could be seen in Metroid Prime Hunters: First Hunt, in Regulator Mode (which is a training hologram) on the floor of a ramped shaft. Presumably, this would function for Space Pirate transport, like the Prime games suggest the tracks' purpose is, since it wouldn't be practical for Samus to use (though she does not have the upgrade to use it in that game and it is merely a hologram representation). More tracks can be seen bridging the floors of some raised platforms on Celestial Archives in Metroid Prime Hunters, also not usable by Samus due to a lack of the Spider Ball upgrade. Their presence in this ancient location suggests that the technology is thousands of years old.

There is a glitch in Metroid Prime that allows Samus to get an early Ice Beam. By looking slightly to the left of a Spider Ball Track and jumping against it, it is possible to climb it without the Spider Ball.

Logbook entries
Metroid Prime: "Magnetic rail system track. In Morph Ball mode, press and hold R * when close to this type of surface. Use Control Stick to move the Ball along the track. Release R * to disengage from the surface. CAUTION: A Morph Ball Bomb will briefly disengage the Ball from the track."

Metroid Prime 2: Echoes: "In Morph Ball mode, press and hold R* when close to this type of surface. Use Control Stick to move the Ball along the track. Release R* to disengage from the surface. Using the Boost ability when on a Spider Ball Track will rapidly launch the Spider Ball from the track. Detonating a Morph Ball Bomb will briefly disengage the Ball from the track.

Metroid Prime 3: Corruption: "While in Morph Ball mode, press and hold Z when close to a magnetic rail. Use Control Stick to move the Ball along the track. Release Z to disengage from the track.

Using a Bomb will briefly disengage the Morph Ball from the track."