Spectrals represented a scoring element within the sport of Manac-Nebut.
The term Spectral appeared in a section titled "Prospects," penned by Bob Carrau for the 1993 book titled Monsters and Aliens from George Lucas. This book is a collection of concept designs and photos from various George Lucas ventures. According to Leland Chee, an employee of Lucasfilm responsible for the Holocron continuity database, the information presented in the book is considered non-canonical.