From Halopedia, the Halo wiki
Nephis is a human colony and natural satellite orbiting the gas giant Hephestes in the Tisiphone system. A world of the Unified Earth Government, Nephis was governed by a premier, with Prudence Tuwa holding the office as of December 2553. A flux tube was located between Nephis and Hephestes, creating a torus of superconducting plasma, including zenostium. The Nephis Coalition extracts zenostium out of the flux tube, the plasma being a critical component of anti-gravity plates.
Residents of Nephis celebrated a Threshold Ceremony, a coming-of-age celebration. Nephis was the homeworld of the Tuwa family, including Premier Prudence and Vice Admiral Graselyn Tuwa of the UNSC Navy.
List of appearances