Huragok
Huragok, or Engineers are actually an artificial species created by the Forerunners. They will only converse with the Prophets or individuals who learn their language. This indicates Engineers are very high in the caste system, however ONI believe them to be prisoners or slaves. The Huragok perform the physical labor of excavating, and gathering data on Forerunner artifacts. In military terms, they are generally a non-militant race. However, at times in the Human-Covenant War they have been placed on the battlefield either as repair workers or suicide bombers. They have also displayed neutrality and even some allegiance to humans such as Lighter Than Some helping the citizens of Harvest escape and another Engineer repairing Ascendant Justice's engines for the Master Chief and even a Needler for him to use in battle. Another example is one Huragok repairing and recovering the Human AI Superintendent and then assisting Captain Veronica Dare and Sergeant Major Avery Junior Johnson in working out what the High Prophet of Truth was looking for in Africa.