Morph Ball

One of the most prominent, integral, and representative items of the Metroid games, the Morph Ball (モーフボール) sometimes called the Morphing Ball (モーフィングボール), or the "Maru Mari," is the Alt-Form of Samus Aran, and allows her to turn into a sphere almost 1 meter in diameter. It allows her to enter small tunnels and openings, which often lead to previously inaccessible areas.

Morph Ball Mode is vital in defeating many bosses from the series, including Amorbis in Metroid Prime 2: Echoes and the Queen Metroid in Metroid II: Return of Samus. In non-Prime games, it usually plays an important role in escaping from enemies, such as in Metroid: Zero Mission. In almost every game, a combination of the Morph Ball and a Bomb is the only way to detach a feeding Metroid.

Upgrades
The Morph Ball has many upgrades, such as the Bomb Module, Power Bomb, Spring Ball, Force Ball, Boost Ball, and Spider Ball. Metroid Prime 3: Corruption introduces the new Hyper Ball ability, which allows Samus to generate deadly arcing tendrils of Phazon energy around her when in Hyper Mode. In Metroid Prime Pinball, the Morph Ball is the ball the player plays with on the pinball machine and introduces the Force Ball.

In the three Zebes-based games, the player acquires it almost immediately after beginning the game.

Appearance
Throughout the series (most prominently in Echoes), the Morph Ball has changed in appearance according to suit upgrades. The Morph Ball when Samus is in possession of the basic Power Suit is a yellow, gold or orange hue and has three grooves which spiral outwards from the center on each side. Between the two halves is a ball of energy, which is believed to be the essence of Samus. The energy varies in color. With the Power Suit the energy is yellow, with the Varia Suit it is most often blue, although it is sometimes green or white. With other suits expansions the energy is often light blue.

In Metroid Prime, the Morph Ball changes after the acquisition of the Spider Ball. The energy inside becomes green and a spherical "dent" appears on the sides, and is filled by a green translucent hologram. It changes color scheme twice after this, to purple plating and a blue core when Samus gets the Gravity Suit, and to black plating and a deep orange-colored core when Samus is infused with the Phazon Suit. In Metroid Prime 2: Echoes, after the Dark Suit is acquired, the Morph Ball becomes more wheel-like in appearance, in accordance to the shoulder pads of said armor. After acquiring the Spider Ball, a large red dot appears on sides of the Morph Ball. After the Light Suit is acquired, the Morph Ball becomes spherical again, but has a spiraling groove on the sides.

In Metroid Prime 3: Corruption, the Morph Ball becomes a Phazon-blue ball with hexagonal tiles over it after the PED Suit is acquired. When the Hazard Shield is collected, extra plating is added to the Morph Ball. Also, if Samus touches a Liquid Phazon enemy while in Morph Ball mode, she will become engulfed by a portion of the creature, which will eat away at her suit.

In Metroid: Other M, the Morph Ball has a different appearance. The ball and energy are yellow with the Power Suit like in past appearances, but there are now three red stripes which spiral out from the centre in the place of the grooves, similar to the Fusion Suit's Morph Ball form. When the Varia Suit is acquired, the energy becomes green and three shorter yellow stripes are placed alongside the red ones, similar to the small blue stripes on Dark Samus's Morph Ball. When the Gravity Suit is acquired, the Morph Ball does not change due to the appearance of Other M's Gravity Suit.

Other appearances
According to a Space Pirate Data "Hunter Weapons" in Prime, the Pirates found the Morph Ball to be a very curious and intriguing technology, but attempts at reverse-engineering the Morph Ball technology all ended in a disaster: the Science Team "wisely decided to move on" after the first four test subjects were horribly broken and twisted after engaging their Morph Ball prototypes.

Dark Samus also possessed a twisted variant of the Morph Ball. She is shown using it in the second fight with her in the Sanctuary Fortress in Echoes, and creates Dark Echoes which can use the Morph Ball during the fight with AU 313 at the end of Corruption. On both occasions, she uses the Boost Ball and is able to generate massive amounts of kinetic energy at once, that propels her around the area at shocking speeds. Dark Samus's Morph Ball is similar to Samus's, and has an eye on each side in Echoes, and it may also in Corruption. It is very hard to actually make out the appearance of Dark Samus's Morph Ball in Corruption, because it is always traveling at great speeds. The energy surrounding it while it is using the Boost Ball also obscures its appearance.

Dark Samus' Morph Ball also heavily resembles the Glire, Glice and Glunder enemies in Super Smash Bros. Brawl. The Morph Ball has limited appearances in gameplay as Samus; her rolling dodge has her literally roll aside to avoid attacks, and her Down-B special "Bomb" transforms her to the Morph Ball and drops the signature Morph-Ball bomb.

Metroid (1986 manga)
"Maru Mari - Get this, and Samus' body will become round, allowing entry into narrow passages."

Official Nintendo Player's Guide
"As soon as you start, go to the left. Jump up and cross the high walls, then you can get hold of the Maru Mari. This is useful for going through walls or narrow passageways."

Super Metroid manual
"You can use the Morphing Ball to make Samus roll into a ball and squeeze into narrow areas."

Metroid Fusion manual
"Use this power to roll into a ball and move through narrow passageways. Press down twice on the Control Pad."

Official Metroid Prime website
"Weapon effect: N/A

Weapon range: N/A

Weapon potential: Medium"

"The Morph Ball is a modular upgrade to Samus Aran's Power Suit, allowing the bounty hunter to roll into a spherical shape. While in Morph Ball form, Samus can place Bombs, activate special switches and squeeze through tight spaces.

Like the Power Suit itself, the Morph Ball is upgradeable via several modifications located throughout Tallon IV."

Metroid Zero Mission manual
"This ability allows Samus' suit to curl into ball form and navigate narrow passageways. (Press down twice)"

Zero Mission Samus Screen data
"Double tap down to take ball form and gain access to narrow passageways."

Metroid Prime 2: Echoes
"The Morph Ball changes your suit into a compact, mobile sphere. Press X to enter Morph Ball mode. Press X again to leave Morph Ball mode.
 * Samus's Notes: Like the Varia Suit, the Morph Ball is modular. There are several modifications that can be added to improve performance."

Metroid Prime Hunters
"SAMUS has the ability to transform into a ball that can move at high speeds and access areas her bipedal form cannot. To enter the alt-form, tap the icon in the lower corner of the touch screen. Use the +Control Pad or A, B, X, and Y buttons to move the MORPH BALL. Use the touch screen for more precise control with gentle strokes in the desired direction. BOOST by quickly stroking in the desired direction or by pressing the BOOST button."

Metroid: Other M On-Screen Tutorial
MORPH BALL

With the Wii Remote held sideways, press A.

DEACTIVATE MORPH BALL

Press A while in Morph Ball to return to normal.

Metroid: Other M manual
"Press A to go into Morph Ball mode and move around small spaces. Press A again to change back."

Metroid: Other M Samus Screen data
"Effect: Changes Samus into a ball shape. Controls: Hold the Wii Remote horizontally and press A."

Brawl Sticker

 * Morph Ball Metroid Prime Pinball - [Weapon] Attack + 5 (Samus, Zero Suit Samus)

Behind the scenes
Exactly how it functions is unknown, but Prime concept art shows a large ball forming around Samus from her suit's material, then shrinking down to its miniature size- in game, a core of energy is visible through the crack between the two sides, indicating that Samus may transform into energy to fit in the smaller ball. On the other hand, Zero Mission design documents refer to the Chozo being capable of "unique transforming into a sphere," implying that the user's body is physically within the ball somehow.

Trivia

 * In the original Metroid, the Morph Ball is called Maru-Mari, meaning "round ball."
 * In Corruption, Samus can perform a jump in the morph ball by jerking the Wii remote up; this also makes double-jumps easier when item-hunting.
 * The only time Samus ever demonstrated the use of the Morph Ball outside her Power Suit was in the original Metroid.
 * In the Prime series, if Samus uses the Morph Ball before jumping from a high ledge, she won't be stunned from the fall like she would normally.
 * In Metroid Prime, Space Pirate logs reveal that they had tried to copy Samus's Morph Ball. However, their prototypes predictably failed, with gruesome results. (e.g: twisted bones and broken limbs).
 * The Morph Ball was slated to appear in Marvel: Ultimate Alliance along with Samus and several of her other abilities, however, they did not appear in the final game due to Nintendo not giving consent. The depiction in the trailer appears to be based on that of Prime as Samus charges forward several times, suggesting the Boost Ball was intended to appear as well.
 * The Morph Ball is featured in the Burger King toy Metroid Challenge, where the ball is controlled through a maze with a magnetic Wii Remote.
 * In Metroid Prime, the Morph Balls for every suit were modelled and skinned by Gene Kohler.
 * Derek Bonikowski researched, animated and tested the Morph Ball in the Prime Series.
 * In Metroid: Other M, when Samus is at critical damage, she'll still breathe heavily when she is in Morph Ball mode.
 * The Morph Ball makes a cameo appearance on the Geothermal Power Plant stage featured in Dead or Alive Dimensions.
 * The concept of Samus transforming into energy and being encased in a small metal sphere is not too dissimilar to the Pokeball in Nintendo's Pokemon series.
 * Coincidentally, in Super Smash Bros Brawl's Story Mode: Subspace Emissary, Samus teams up with the Pokemon series mascot, Pikachu.