Multispectrum particle lifeforms were a form of non-corporeal beings.
The Borg once encountered such a race, which they referred to as Species 5973, in Galactic Cluster 8. When being told by Neelix of the USS Voyager's encounter with an unknown, gaseous lifeform in 2376, Azan guessed that it was a member of this species, although this was denied by Neelix. (VOY: "The Haunting of Deck Twelve")