The nialig was a non-corporeal, electrostatic animal species native to Rigel V.
History and specifics[]
Researchers studying the nialig found that subjecting one to a polarizing induction field would disrupt and disperse its structure, but it would be able to reform within 20 minutes. Prolonging exposure beyond 20 minutes would result in its death.
In the year 2268, when the body of Captain James T. Kirk was possessed by the Midgwin telepath Yarblis Geshkerroth, Geshkerroth researched the nialig, as well as other ways of killing similar lifeforms, in order to destroy Kirk's surviving disembodied consciousness. (TOS novel: Ghost-Walker)