- You may be looking for the list of spaceborne species.
The spaceborne entities are creatures that are able to live and travel in the vacuum of space and have the ability to transform into a variety of other objects.
Its mate, transformed into a strange ship, fired on the neighboring "Old Bandi City" until the first entity was freed by the USS Enterprise-D. The two creatures left the system, destination unknown. (TNG: "Encounter at Farpoint")
In Orion's Hounds, part of the Star Trek: Titan novel series, the USS Titan under the command of William T. Riker encountered this species again. They were variously referred to as "star-jellies" by the Titan crew and "skymounts" by another species who used them as space-traveling vessels.