Black fog

The Black Fog appears and possesses an Alpha Splinter.

Ing take the form of a gaseous "black fog" (as named in Metroid Prime: Episode of Aether) when they travel through the light dimension. This is the only way for an Ing to survive for a short period of time on light Aether, and it is used to possess a nearby bioform or mechanoid, turning the victim into a Darkling.

Despite the name, Ing which take this form become a cloud of mostly purple particles. Although Samus is unable to cause any damage to Ing that are in this state, if she destroys the intended host creature before the Ing manages to reach it, the Ing will aimlessly float around in its black fog form for a short while before finally succumbing to Light Aether's atmosphere and exploding. This strategy, however, is limited to only a handful of minor enemies and must be executed very quickly, as the black fog will usually make contact with a host mere seconds after appearing. Once started, a creature's tranformation into a Darkling cannot be stopped.

Episode of Aether

In Episode of Aether, the Federation Marines report that a "black fog" had possessed the Splinters attacking them, rendering the creatures invincible and making it easy for all but four of the Marines to be killed. Samus finds one of these survivors being attacked by the Alpha Splinter and intervenes, managing to kill it. The Marine urges her to finish it off before the fog comes, but she is too late. Initially unable to destroy the resurrected Darkling form, she finishes it off with an Overblast at point blank range.

In Metroid Prime 3: Corruption, Dark Samus takes on a similar form to absorb the corrupted and dying Bounty Hunters. Like the black fog, in this form she is gaseous and cannot be harmed. The gaseous form features Dark Samus' visor while swooping in and out of the scene like a bird.