Chiton armor is a form of natural chestplate armor, which creates a thick, ribcage-like covering over the core of an Omega Metroid. This means that unlike Alpha, Gamma or even Zeta Metroids, the Omega Metroid can defend its weak point. This armor is a new ability of the creature in Metroid: Samus Returns, which has expanded the Omega Metroid battles from Metroid II: Return of Samus.
Samus can destroy the chiton armor gradually with Missiles, Super Missiles and Ice Beam shots, and can destroy it instantly with a Power Bomb. When the armor is destroyed, the Omega Metroid recoils back twice, and the exploding armor releases Missile and Super Missile Ammo, and Energy Capsules. After the armor is removed, the Omega will attempt to lunge at Samus, opening itself up to a Melee Counter followed by a Grab Sequence where Samus can inflict damage to the membrane. After the Grab Sequence is over, the Omega Metroid will regenerate its armor, although the chiton will be visually thinner and cover less surface area than before. After it is broken a second time, the armor will not regenerate, leaving the membrane exposed for the remainder of the battle.
- Omega Metroid (p. 22)
- "Evolution has also done away with the Metroid's trademark weak point: the core. While the core is still there, the Omega's chiton armor plating hides it deep in its chest. The only way to reach it is to force your way in with explosive attacks, but even then, you have a short amount of time to strike before the chiton self-repairs and covers the core once more."
- It should be noted that the correct term for this armor would be chitin, and not chiton. However, the only source that names this armor uses the latter term.
- Chiton armor, or at least a similar predecessor ribcage covering its membrane, can be seen on the Omega Metroid's original design in Return of Samus and especially Metroid Fusion. However, unlike in Samus Returns, this early chiton armor is completely aesthetic and does not protect the Omega Metroid in gameplay.
- Queen Metroids also appear to possess chiton armor, although it does not fully protect the Queen Metroid's membrane from attacks (as seen in Metroid: Other M).