How many Shield-Worlds have been located by both the UNSC/ONI and the Covenant?
and of them What are their names?
Onyx/Trevelyan (UNSC during its colonial expanse before it became a top-secret ONI site in Halo: Ghosts of Onyx)
Requiem (UNSC/Covenant Remnant during the events of Halo 4)
Shield World 0459 (UNSC/Covenant during the events of Halo Wars)
Shield World 0673 (Discovered by the Sangheili from the Ussan clan who hid from the Covenant during the Covenant’s founding in Halo: Broken Circle)