Like all other Metroid forms, the Fission Metroids are energy-based lifeforms with transparent upper bodies. Also like other forms, they are energy vampires and thereby feed upon unseen energy from various other bioforms, and do so through the use of two sets of claw-like mandibles which protrude from the lower half of their body; these latch onto prey, perhaps even puncturing their skin and latching onto them from the inside.
When struck with any sort of weaponry, the Fission Metroids undergo binary fission as a defensive measure, endowing each new Metroid with invulnerability to most conventional weaponry. Unfortunately for them, this effect is unstable, and therefore during the split each Fission Metroid will become particularly vulnerable to a particular energy type, allowing someone with such weaponry to utilize this weakness against them. This vulnerability seems likely random due to the chaotic nature of Phazon mutation. The only two known ways to avoid a Fission Metroid's binary fission is to eradicate them with either power bombs or a Phazon Beam.
For some unknown reason, Fission Metroids do not seem to require going through the initial egg stage of Metroid life. Fission Metroids have been witnessed spawning directly out of pools of Phazon.
Fission Metroid Subtypes
There are four subtypes of Fission Metroids, each being only weak to power bombs, phazon beams, and one other specific beam.
- Power Metroid: Vulnerable to power beam technology.
- Wave Metroid: Vulnerable to wave beam technology.
- Ice Metroid: Vulnerable to superchilled ice particles.
- Plasma Metroid: Vulnerable to superheated plasma.