Precursor technology was extremely advanced, to the point that the Forerunners labeled it Tier 0. Some Precursor artifacts were known to precede the Forerunners by hundreds of millions of years, and were durable enough to be cycled inside planets' crusts by plate tectonics.[5] Precursor artifacts were often encountered by Miners, who obtained and recorded them but rarely held any particular interest in them. The most coveted Precursor artifact among the Forerunners was known as the Organon, which was allegedly capable of activating all other Precursor artifacts.[2]
Among the most impressive of the Precursors' structures were the enormous orbital arches and unbending filaments, which were used to connect entire worlds and solar systems.[6][7] Precursor technology was amazingly durable, and was almost totally impervious to all forms of conventional damage. However, the Halo Array's energy pulse has been shown to be able to utterly destroy Precursor structures. When Charum Hakkor was used as a test bed for one of the Halos, the weapon's firing shattered every Precursor artifact on the planet. Precursor construction material was gray-silver, and would shatter along crystalline planes if broken.[8]
Precursor technology is believed to have been based on what Forerunners called "neural physics": The concept that inanimate matter and thought are inextricably linked. It is theorized that the Halo Array, being neurological weapons, are one of the only ways to destroy or otherwise damage Precursor artifacts. This could also explain the lack of any Precursor ruins in modern society (circa 2553 CE) as most, if not all, would have been destroyed when the Halo Array fired and sterilized the galaxy at the end of the Forerunner-Flood war.
