"What's the matter? All I said was that Komaytos look like little Metr—" Non-canon warning: This article or section contains information that may not be considered an official part of the Metroid series in the overall storyline by Nintendo.
Phase Sprites are unused creatures from Metroid Prime 3: Corruption. They have a logbook entry, as well as animations and a textured model, but were for some reason never used in the game.
"Morphology: Phase Sprite. Emits bursts of energy capable of blinding visor systems. Phase Sprites travel in large collectives for safety. Each collective is spawned by a Sprite Nucleus--a larger, brighter Sprite that the others orbit as they search for sustenance. As a defense mechanism, they can render themselves invisible. If threatened, they will generate a bright burst of light and radiation that can temporarily neutralize sensors and powered systems."