The Calamarain were intelligent non-corporeal lifeforms that existed as swirls of ionized gas. Their language could not be processed by the universal translator due to a lack of referents for establishing a translation matrix. They could generate Berthold rays to scan others, and high-energy tachyons for attack.
The Calamarain were once tormented by Q, who insisted that he did nothing "bizarre" or "grotesque" to them. When Q lost his powers in 2366 and was exiled to the USS Enterprise-D to live as a Human, the Calamarain sensed the chance for revenge and attacked Q and the Enterprise. To save the ship, Q took a shuttle to divert the Calamarain's attention away; this noble deed convinced the Q Continuum to restore his powers. Q immediately attempted to exact retribution against the Calamarain, but Q2 forced Q to let them go without harm. (TNG: "Deja Q")
The Calamarain appear in the The Q Continuum novels, where they attempt to prevent the USS Enterprise from breaching the Galactic barrier and allowing the malevolent entity 0 to re-enter the galaxy. Ultimately, they temporarily join with Q and use their combined powers to defeat 0.