Fluorescent plankton

"Fluorescent plankton filled our cave"

- Verse from "If Only I Could Let Go and Cry"

Fluorescent plankton was a type of luminous plankton that dwelled in caves. They were cited in a song called "If Only I Could Let Go and Cry".

Behind the scenes
Fluorescent plankton was mentioned in Monsters and Aliens from George Lucas, a book published in 1993. Lucasfilm employee Leland Chee, who maintains the Holocron continuity database, has indicated that information contained in the book is non-canonical.