Dark Echo

A Dark Echo is a copy of Dark Samus formed from Phazon energy. They possess a simple Phazon-based copy of the Power Beam, along with some of Dark Samus's other moves, and a far smaller supply of health than Dark Samus, and thus can be destroyed easily.

They exist only as decoys to distract Samus as Dark Samus drains Phaaze's energy in the final battle between the two, and to that effect, they can create the illusion of draining energy as well. Dark Samus will use two at first, but later can create three after taking enough damage. They will all attack at once, making it hard to target one of them at a time. They will use (as stated before) Dark Samus's version of the Power beam and some of her other moves. Dark Samus can also perform another move with the Echoes, in which she and the Echoes will levitate a few inches off the ground and then move around the room rapidly, making them difficult to hit until the move ends. They can also temporarily fuse back into the real Dark Samus, but while they are fused with her, Dark Samus will be covered with a purple energy shield and be invulnerable until the Echoes seperate from her after a period of time. If the real Dark Samus has taken damage, after an amount of time both she and the Echoes will perform her energy-recovery move, however, if the Samus acts fast enough, the Echoes can be destroyed and the real Dark Samus can be damaged before recovering all her health, due to the Echoes' extremely low health. Both the X-Ray Visor and the Scan Visor can tell them apart from the real Dark Samus. Echoes also have black visors, while the real Dark Samus has a bright blue visor. Destroying the Echoes will reveal powerups, such as Anti-Phazon Units. As said before, this is easy as Echoes are relatively easy to kill and actually the fact that they can be killed is another way to differentiate them from the real Dark Samus, since the player can tell whether or not one of them is the real Dark Samus depending on whether they die after a number of shots.

Even weaker Dark Echoes are generated by Dark Samus when she is controlling Aurora Unit 313, who have the ability to use Morph Ball. They will use the Boost Ball to shoot around the arena, but they are easy to dodge and subsequently kill for powerups.

Scan
Metroid Prime 3: Corruption: ''Morphology: Dark Echo. Facsimile created by Dark Samus. Susceptible to Hypermode attacks.''

Trivia

 * They are presumably named after the game Metroid Prime 2: Echoes. The Japanese version is called "Metroid Prime 2: Dark Echoes".
 * If one or more Dark Echoes are next to Dark Samus when it is destroyed, Dark Samus herself will take additional damage from the impending explosion.
 * They also appear in a Diorama along with AU 313, in the game's Extras menu.
 * The explosion and sound effect when Dark Echoes die is similar to the way Metroids die in Metroid Prime, which suggests that they are Metroids spawned by Dark Samus just like Metroid Prime could spawn Metroids in Prime.
 * When scanned, the pictures for the scan are warped red versions of Dark Samus' images, suggesting that their similar nature to Dark Samus made the Scan Visor malfunction.