Spider Ball

The Spider Ball is a special power-up for the Morph Ball, featured in Metroid II: Return of Samus, Metroid Prime, Metroid Prime 2: Echoes, and Metroid Prime 3: Corruption.

Description
In Metroid II, the Spider Ball is one of the most important upgrades to exploration. It allows Samus to adhere to walls and ceilings when in Morph Ball form, thus allowing her to reach nearly anywhere in the game.

The Spider Ball is acquired in Metroid Prime by defeating Thardus, in Metroid Prime 2: Echoes by defeating the Spider Guardian, and in Corruption in the Powerworks on SkyTown. In these games, the Spider Ball allows the Morph Ball to cling to magnetically conductive ground areas, via electromagnetic capabilities. Normally, it is used to climb specially adapted railing called Spider Ball Tracks. If a Morph Ball Bomb is deployed, the Morph Ball will make a vertical "hop" as if on regular ground, disconnecting her from the rail for a second. If the Boost Ball is used (only in the later two Prime games), she will leap in the opposite direction from the track, often with enough power to shatter thick glass.

The Spider Ball is often used to gain access to hidden areas with a Missile Expansion, Energy Tank, or similar upgrades. Early, simpler upgrades might be a straight shot to the prize, but many involving the Spider Ball require the player to go through complicated puzzles, including the use of Bomb Jumps, Boost Ball leaps, and dropping from one track to another or grabbing onto a side track while falling. There have been a few bosses that required use of the Spider Ball to defeat, notably the Power Bomb Guardian, the Emperor Ing, the Quadraxis, and the Caretaker Class Drone.

Appearance
In Metroid Prime, the Spider Ball greatly alters Samus's Morph Ball appearance. A large dent covers both sides of the Morph Ball and glows with the same color as the core. Transparent glass covers the dent and retains the Morph Ball's roundness. Oddly enough, when the Fusion Suit mode is activated, the Spider Ball does not appear on the Fusion Suit's Morph Ball form as it would regularly, though it still allows Samus to climb magnetic surfaces.

In Metroid Prime 2: Echoes, Samus acquires the upgrade while in the Dark Suit. The only change is that the red orbs on the sides are enlarged. It is unknown how, or if, the Light Suit is affected, as the suit has no similarities to the previous one. At the beginning of the game (prior to losing her power-ups), if Samus looks through her inventory to her morph ball modes, it shows that she has the Spider Ball ability at that time. However, it shows a picture of the Dark Suit morph ball even though she was wearing the Varia Suit.

In both Metroid Prime 3: Corruption and Metroid II: Return of Samus the Morph Ball's appearance is not changed.

In the Prime series, a small band of energy connects Samus to the magnetic rail when activated. This bond is easily broken by the Morph Ball Bombs and Boost Ball.

Metroid II: Return of Samus manual
''"When Samus has assumed the ball shape, she can activate the Spider Ball by pressing down on the Control Pad. This “sticky ball”, gives her the power to move across the walls and ceiling unhindered by gravity. To maneuver, use the Control Pad. To return to the regular ball, press the A Button." ''

Official Metroid Prime website
Weapon Effect: N/A

Weapon Range: N/A

Weapon Potential: Non-Lethal

"The Spider Ball allows Samus to take advantage of special Spider Ball Tracks while in Morph Ball form. With the Spider Ball, Samus can cling to these surfaces and roll over obstacles, across walls and even upside down. The Morph Ball Bomb can be used to trigger a Bomb Jump while Samus is attached to a Spider Ball Track."

Metroid Prime manual
"Once Samus finds the Spider Ball, she can magnetically attach herself in Morph Ball mode to specific magnetic tracks that run throughout Tallon IV's environment. To activate the magnet, simply press and hold the R Button. The Morph Ball will stay fixed to the track as long as you hold the R Button—tilt the Control Stick to move along the track and release the R Button when you wish to drop off the track. You can propel yourself upward by laying Bombs while attached to a track."

Metroid Prime 2: Echoes manual
"Once Samus finds the Spider Ball, she can attach herself to specific magnetic tracks. To activate the magnet, simply press and hold the R Button. The Morph Ball will stay fixed to the track as long as you hold the R Button—tilt the Control Stick to move and release the R Button when you wish to drop off. You can propel upward by laying Bombs when attached, or launch out by using the Boost Ball function."

Trivia

 * In Corruption, the Spider Ball is the only item held within the hands of a Chozo Statue. In the entire Prime Series this and one Chozo Artifact are the only items to be found in such way.
 * It is unknown why the Spider Ball can cling to virtually any surface in Metroid II: Return of Samus despite the lack of magnetic tracks, which are used in other games.