Key of Osanalan
From Halopedia, the Halo wiki
This article is a stub. You can help Halopedia by expanding it.
The Key of Osanalan is a Forerunner object underneath the city of Cleveland, Ohio on Earth. [1] As revealed by a captured Colonel James Ackerson, without the Key, the Halos will not properly activate. From Ackerson's tortured admission it is implied that the previous Halos failure may have been due to the absence of this Key. Outside of Halo: Uprising, no mention of the key is seen in Halo 3, and Master Chief activates the replacement Installation 04 successfully even without the key. However, the key could be required for a full Array activation, but not for single detonations, as a sort of stop-gap measure to insure the galaxy is not wiped out by accident. The Prophet of Truth, despite wanting to activate the Halos, did not search for the object vigorously, indicating that the Key may not be needed at all.
