Fission Metroid

Fission Metroids are mutated Metroids born directly from Phazon pools or from Tallon Metroid Larvae exposed to Phazon. They lost their ability to develop beyond the larval stage and reproduce normally but can now reproduce by mitosis, which allow them to split into two identical individuals.

Behavior
Fission Metroid looks identical to regular Metroid Larvae aside from their colorless internal organs. After sustaining enough damage from any weapon, a Fission Metroid will divide into two randomly-colored duplicates, which give them immunity to almost the entirety of Samus Aran's arsenal. Their new immunity gives them the internal color of their main weakness. All Fission Metroids are also vulnerable to Metroids and Power Bombs, the latter of which can destroy them instantly. The four types of Fusion Metroid are:
 * Yellow: Vulnerable to the Power Beam and Super Missiles.
 * Purple: Vulnerable to the Wave Beam and the Wavebuster.
 * White: Vulnerable to the Ice Beam and the Ice Spreader.
 * Red: Vulnerable to the Plasma Beam and the Flamethrower.

Temporary Scan
"Morphology: Fission Metroid Metroid with the ability to split into two forms."

Logbook Entry
"The Fission Metroid is a mutant, capable of splitting in two. This split endows the new creatures with invulnerability to most weaponry. This effect is unstable, resulting in weakness to a type of weapon fire. The vulnerability appears to be random, due to the chaotic nature of Phazon mutation."