Anaphasic lifeform

An anaphasic lifeform is a sentient entity made up of anaphasic energy, which differentiates such entities from solid matter-based symbiotic lifeforms.

Being extremely unstable, such lifeforms require some sort of conduit to maintain molecular cohesion and a corporeal host with compatible biochemistry in order to take physical form.

They can also travel along a standard power transfer beam, and leave traces of anaphasic radiation in their wake. When bonded to a Human, the host's appearance may change, such as a change in the eye color.

Ronin was an anaphasic lifeform. 

Background
The anaphasic lifeform, in its non-corporeal form, was a computer generated effect (CGI), using for the first time in televised Star Trek the  software (at the time still the software component of the Amiga Video Toaster Suite package, and later on the software package of choice for the Star Trek television franchise), provided by Digital Magic's Joe Conti and Tim McHugh. It was a conscious effort to gain more creative control in contrast to the traditional usage of liquid nitrogen against black velvet, called by VFX supervisor David Stipes, "an act of God", due to the fact that once employed, getting a good usable shot, using this method, was very much a "luck of the draw" process.(Star Trek: The Next Generation Companion, p. 281) Digital Magic continued to experiment with LightWave 3D software in the remainder of the series, creating amongst others the plasma stream in the later episode.

Anaphasische Lebensform