Trove

This Flood-controlled Shield World was a world well outside the spheres of influence of both the UNSC and the Covenant. An artificially constructed Forerunner installation, it was a variation upon the Shield World concept, originally intended to protect sentient lifeforms from the effects of the Halo Array.

The Covenant secured a relic on Harvest, pointing them towards another UNSC colony, Arcadia. Another relic directed them to the location of the Shield World, where the Arbiter hoped to use the Shield Worlds' stored Forerunner warships to crush the UNSC quickly, rather than wage the protracted war that would characterise the Human-Covenant War. To prevent this, the sacrificed its FTL Reactor to create a chain reaction in the artificial sun in the center of the Shield World, destroying it from within.

Despite the fact that the Shield Worlds were created as a haven from the Array and the Flood, the external surface is heavily infested with Flood biomass, with forms of various types freely roaming across the surface. Sentinels are a rarity on the outside, but this changes within the center, where the many Forerunner constructs work to prevent the Flood from claiming the interior as well, without much effect. .

Comparisson Onyx Installation
Unlike Onyx, which was made up of trillions of Sentinels, from which a planetary surface had formed, this world was built in a method similar to a Halo Installation, though on a much larger scale, being a hollow structure with a planetary surface on top and the interior and exterior being supported by numerous pillars. Inside this is a more familiar construct of a shipsized portal allowing access, via a portal based in the surface of the interior world, to the Shield World, which, much like Onyx, appears to be in a slip space bubble, supported with a artificial sun. However, unlike Onyx, it was not designed as a bomb shelter, but as some sort of harbour, shipyard or hiding place for ships, as it contains The Apex.