As WookieepediaWookieepedia explains:
Grebleips' [Spielberg spelled backwards] species are a cameo appearance of the famous aliens of Steven Spielberg's 1982 film E.T. the Extra-TerrestrialE.T. the Extra-Terrestrial.
These creatures were inserted in the movie Star Wars Episode I: The Phantom MenaceStar Wars Episode I: The Phantom Menace to make good on a promise—after Steven Spielberg included a Yoda cameo and Star Wars toys in E.T.,
George Lucas promised to include an E.T. cameo in the next Star Wars film he made —The Phantom Menace.
While this is primarily an easter egg, and E.T. is probably not meant to be taken as part of Star Wars canon, some Star Wars references in E.T. can be reinterpreted in light of the E.T. references in Star Wars.

