Annona was a powerful, intelligent being made of energy on Spherus Magna that fed on the dreams of other beings. Physically, Annona appeared to be a brilliant sphere of energy from which crimson tentacles lined with spines sprouted. She moved by levitating and possessed a number of special abilities related to the mind, including the ability to cast other beings under illusions or enslave their minds. She relied on other beings' dreams for sustenance; when she fed on dreams, those affected lost their ability to dream while sleeping, which led to madness and eventually death.
Annona claimed that she existed on Spherus Magna since before the Great Beings were born. When she tried to feed on their minds, the Great Beings were instead inspired to greater levels of creativity and drove Annona beneath the surface of Spherus Magna, where she hid in fear for thousands of years. At one point, while remaining hidden, Annona fed on the dreams of the Iron Tribe and decimated its people; the true cause of this "dreaming plague" was not discovered for thousands of years. Annona also claimed to be the one who originally granted the female Skrall their psionic powers.
Around the time of the re-uniting of Spherus Magna after the battle between Mata Nui and Makuta Teridax, Annona emerged from hiding once again and immediately confronted the golden being. Annona was eventually forced by the golden being and Sahmad to inhabit a reality filled with other beings like herself, consigned to feed off each other and eventually die out.