Ripper

Rippers are small floating tortoise-like creatures which move horizontally back and forth, and are best known for their near-invulnerability: a Ripper can only be killed with a Super Missile, the Speed Booster, or the Screw Attack. Because of their slow movements, they can be quite inconvenient when moving through halls or shafts (particularly when using the Wall Jump technique). However, in Metroid: Zero Mission, there are purple-colored Rippers who move noticeably faster than the common brown variant.

Within the games, Rippers are commonly frozen and used as platforms to reach otherwise inaccessible areas. In Super Metroid, they can also be used as Grapple Points for the Grappling Beam to cross over hazards and with enough momentum, Samus can throw herself high into air; the Rippers stop moving as soon as they're connected to Samus. They have been encountered only on Zebes, though their X-parasite mimics were found on the Biologic Space Laboratories in Metroid Fusion.

A Galactic Federation Ripper specimen was dubbed SR-478. It is unknown whether the planet SR388, also sometimes written as the very-similar SR-388, is related to this specimen name. 

Note: "Ripper" is also slang for a person with a constant case of gas. Which leads one to believe the Nintendo product translators were having fun with chilli and matches on the day this creature was named. "He let one rip!"

Variations
Ripper IIs are red or purple-colored Rippers which travel much faster than not only their rust-colored counterparts, but also surpass the speed of the purple Rippers. Ripper IIs, having exhaust flames behind them, are apparently jet-propelled. These creatures generally have more bulk than common Rippers and are more rectangular in shape. It is unknown if Ripper IIs are naturally born or evolve from Rippers (as mentioned in the 1986 manga) or if the Space Pirates have somehow modified them. These creatures can also be used as Grapple Points. The Tripper seems to be a variant of the Ripper II.

The Winged Ripper is a unique Ripper, seen only during a boss fight in Metroid: Zero Mission. The Winged Ripper's defining characteristic are its small wings which allow it to travel in a circle, rather than the usual back-and-forth patrol. The wings on this Ripper appear similar to that of the Cow. If timed right, the boss can kill this Ripper as it falls to the ground upon defeat; this is the only way to kill the Winged Ripper, as it is invulnerable to both the Screw Attack and Super Missiles.

All of the Rippers seen in Metroid Fusion are X Parasites that have either infested the bodies of normal Rippers or are simply mimicking the creatures. Rippers are one of the very few creatures that have not been changed physiologically by the parasites in any way: the Ripper-X can be seen as perfect imitations.

Metroid Prime


Rippers do not appear in Metroid Prime on the Frigate Orpheon or on Tallon IV. However, an unused creature that resembles a Ripper appears in concept art and has a model in the game's data, even unused scan images that appear in concept art as well (in a collection of Scan Visor panels). It also appears on page 39 of Metroid Prime and Metroid Fusion: Prima's Official Strategy Guide and on page 119 of the Metroid Prime Official Strategy Guide by BradyGames. The creature does not appear to have any limbs, so its method of locomotion is unknown. It would possibly have been able to fly. It appears to be some sort of leech, with a hardened shell exterior. Two large, circular green eyes are present at the sides of the creature's "head", and it has a sort of "hook" at the bottom, which may have been intended to serve as a Grapple Point for Samus. A funnel is also featured on the rear end of the creature; this may have been where the plasma propelling the creature was exhausted. Due to it resembling a Ripper, it is indeed possible that the Ripper was planned for, but scrapped in Metroid Prime for reasons unknown. The Glider creature in the game appears to be the Tallon IV equivalent of a Ripper.

Metroid manual
"These strange creatures do not have brains. They simply fly around sluggishly in straight lines."

"These slow creatures don't attack but fly aimlessly in straight lines. It is wiser to run away from them than to try fighting them."

Ripper II: "These Rippers are more advanced than the Rippers who appear in the rocky zone. They can spit fire and fly at high speed. They look the same as the other Rippers but they fly a lot faster."

1986 manga
"Beams bounce off this organism's hard shell. It moves horizontally left and right. It is possible to destroy the red Rippers with Missiles."

Official Nintendo Player's Guide
"These creatures fly slowly and don’t attack. It is wiser to avoid them."

Super Metroid manual
"The armor of these flying creatures is so strong that standard beams cannot beat them."

Super Metroid Nintendo Player's Guide
"These enemies can be frozen to use as steps in long shafts."

Metroid: Zero Mission manual
"For the most part, these organisms just slowly fly through the air in straight lines. They are impervious to most attacks."

Official Website
"SPECIMEN ID# SR-478 ''"Exterior armor plating makes this specimen a hearty foe. Keen vision suggests a preference for deep, cavernous areas - probably to hunt for food. DANGER LEVEL: LOW."''
 * "Armor plate"
 * "Light-sensitive retinas"
 * "Powerful legs"

Trivia

 * Rippers feature prominently in the Catch Mode of Tetris DS in the background.
 * The Ripper's in-game sprite seems to resemble a turtle due to the hard shell and head, however, without limbs.
 * The Ripper is one of a few objects that will shake when Samus Wall Jumps off them in Super Metroid.

Gallery
Ripper