pulled this off of Halowiki
interesting could it be the precursors we face?
any info from Halo wiki
Not much is known about them, but information that can be found by text from the logs stored in the Terminals around the Ark indicates it is possible that the Forerunner 'Mantle' (Guardians of the Galaxy and all life) was handed down from "legends of the past": the Precursors. It has been presumed that the Precursors viewed the Forerunners as their own legacy, continuing their work after they departed, much in the same way Forerunner lifeworkers (including the greatest lifeworker: the Librarian) viewed Humanity before the activation of the rings. Having obtained the status of Tier-0, it is likely that the Precursors can travel between galaxies.
Precursors are described as "very large", with 4 upper limbs and 2 legs. Also having an "ugly head shaped like arthropods" - like spiders or crabs - they have oval, faceted slanted eyes and a "flat face". Coming from the back of the head is a long tail with a 2 meter barb coming out of it. Whether this is the way all Precursors look has yet to be revealed, but this is the way the prisoner on a Pre-Human world is described.
It is also revealed that this prisoner is the last known Precursor, and that every other Precursor had been ruthlessly killed in a Forerunner-Precursor war almost 150,000 years before the events of Halo and that their answer is at hand - implying that a Proto-Flood form (described as a fine dust, contained in hundreds of glass cylinders) were created as revenge or as a failsafe.
"We meet again, young one. I am the last of those that gave you breath and shape and form, millions of years ago.
I am the last of those your kind rose up against and ruthlessly destroyed.
I am the last Precursor.
And our answer is at hand."
While this is official canon, as the book was written with assistance from 343 industries and Bungie Studios, it would seem to contradict the account of events as described by the Terminals from Halo 3. For in Halo: Cryptum it is discovered that the Didact spoke with this last Precursor. Yet in the Terminals the Didact is answering the Librarian saying that the mantle has not failed them (he is referencing the Forerunners, his own species). He further says that "We can halt this thing!" (Note that he is referring to the flood) "And follow in Their footsteps." Since he is talking about the forerunners inheriting the mantle from the Precursors, and following in their footsteps in that manner, it would conflict with the canon in the book. Therefore it may be inferred that the Flood were created as a failsafe, but slipped beyond Precursor control. It is also important to note that the humans have been identified as the descendants of the Precursors in Halo: Contact Harvest, meaning that the surviving Forerunners could have recognized this, referring to the early humans (who had managed to defeat the Flood with their San 'Shyuum allies) as if they were Precursors.
Original Link in halo wiki
thoughts?