Interphasic Organism

The Interphasic Organisms are parasitoid lifeforms which exist in an interphasic state, undetectable by Human senses.

Biology
The creatures attach themselves to the epidermal layers of their host and use osmotic tendrils to feed on the victims' cellular peptides. If no treatment is pursued, the infestation spreads until killing the host. Unfortunately, the parasites leave no clearly detected symptoms, and cannot be detected even by a tricorder, requiring an interphasic scanner instead.

History
These organisms were present on planet Thanatos VII when a newly developed interphasic fusion process was used to build a warp core conduit, which inadvertently attracted the creatures. Being able to survive within the plasma conduit, the organisms infected the starship Enterprise when the device was installed.

Besides attaching themselves to the crew and physically damaging the warp system, the organisms also emitted an interphasic pulse which interfered with the workings of Data's positronic brain, causing him to experience strange dreams and hallucinations. Fortunately, it was found that the parasites could be destroyed by an interphasic pulse of high frequency.

Appearances

 * Star Trek: The Next Generation, s07e06, "Phantasms" (1993)