|Universe||Men in Black Universe|
|Language||capable of learning|
|Appearances||Men In Black II (first appearance; death)|
Jeff is most likely lithotrophic as it has been mentioned that he eats inorganic garbage and he was seen biting off half of a subway train.
Jeff is one of the many extraterrestrials whose existence is kept in secret by the Men in Black. Zed mentioned that he remembers when Jeff was as small as a regular Earth worm, implying that Jeff may have been born on Earth, or lived on it for most of his life.