Species 8472, known to the Klingons (and generally in-game) as the "Undine", is a powerful race which is native to a different dimension called fluidic space. The Undine have been shown to be shape shifters and their technology tends to appear organic.
8472 was the Borg designation for a tripedal and apparently highly xenophobic non-humanoid species whose actual name is unknown. 8472 was first encountered by the Federation starship USS Voyager in the Delta Quadrant in 2373. The species originates from a dimension called fluidic space, accessible by quantum singularities. (VOY: "Scorpion", "Scorpion, Part II") They are believed by the Borg to be the ultimate form of biological evolution.
- Species 8472 at Memory Alpha, the Star Trek Wiki.