Anaphasic lifeform
From Memory Alpha, the free Star Trek reference
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 eyes change to the color green.
