Huge, jellyfish-like lifeforms that could turn energy into matter, one of which was captured and forced to serve as Farpoint Station.
These spaceborne creatures had a translucent, jellyfish-like form and the ability to convert energy into solid matter, taking on almost any shape they chose. They were intelligent and formed lasting bonds with their mates.
In Encounter at Farpoint, the Bandi had captured one of the beings and used it as Farpoint Station, feeding it just enough energy to keep it alive while it shaped itself into whatever they wished. Its mate arrived and attacked the Bandi city. Picard uncovered the truth, had the Enterprise beam energy to the captive, and the two creatures reunited and departed together.