Faun Hakkor is a planet in the Charum Hakkor system, which was once settled by ancient space-faring humans. It shares its system with Charum Hakkor, Ben Nauk, and twelve other planets that were mined for ores and volatiles.
During the Siege of Charum Hakkor in the human-Forerunner wars, Faun Hakkor became under attack by Forerunner forces as well. While its planetary militia and military forces fiercely defended the world, Faun Hakkor's military installations and personnel numbers were significantly less than Charum Hakkor. While the world was captured by the Forerunners, a majority of its flora and fauna were left unharmed. Following the war, the Forerunner Lifeworker rate ensured the surveying of Faun Hakkor's remaining species.
Around 97,495 BCE, the system was the test site for Installation 07, one of the twelve original Halo rings. The Halo was set to a low power setting, but still managed to kill every organism with a nervous system on the planet; all that remained were primitive organisms such as mosses, fungi, and algae. The planet then went into a state of gradual ecological collapse. The lack of pollinators led to the rapid extinction of flowering plants, while the world's water bodies were filled with decaying matter.
43 years after Installation 07's test-firing, after the Didact was awoken on Erde-Tyrene from his Cryptum, he took his ship to the Charum Hakkor system to find out what had happened during his exile. After finding Charum Hakkor in ruins and barren, he was mortified to discover that life on Faun Hakkor had been eradicated. The Didact later left for Janjur Qom to see the current status of the remaining San'Shyuum.
Similar in size to Charum Hakkor, Faun Hakkor's surface was covered in green vegetation; jungles and dense arboreal forests. The planet had several oceans surrounded between mountain ranges. However, following the end of the human-Forerunner wars, the planet was scarred by craters, overgrown vegetation, and vast regions of the planet were burned and flattened. The Pheru were an animal species indigenous to the planet, and were popular amongst humans and San'Shyuum as pets. Faun Hakkor was also home to a type of semi-sentient tree, forests of which covered the planet. The trees had acquired a form of long-term intelligence, using insects, viruses, bacteria, and fungi as carriers of genetic and hormonal signals in order to communicate with each other over centuries. Despite their intelligence being unlike that of most sentient beings, these trees were among the organisms killed by the test-firing of Installation 07.