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Annona is one of the Nomai who came to the Solar System via the Vessel. He was on board Escape Pod 2 together with Rhus, Bur, Melorae and Coleus, which landed on Ember Twin. After settling down in the Sunless City he was involved in speculations about the Quantum Moon. He hypothesized about the macroscopic quantum mechanism of the Moon. The conversations can be found on the surface of Ember Twin next to the Quantum Moon Locator.
He also had knowledge about building Warp Cores, and the Advanced Warp Core in the Vessel might have been his design. Poke mentions that Annona was her Mentor for a short time. During the Ash Twin Project, in which his knowledge could've been of help, he is said to be already dead.