Okay this is What i believe so don't get all butt hurt.

Could the location we seen in the new halo trailer been one of the two lesser Arks i believe so in this screenshot from the trailer you can clearly see a Planet/Moon in the background.

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As you can see in the image the two location are extremely identical could this be installation 00.

Now you may be wondering what Mendicant Bias has to do with any of this.

Well in Silentium Rebirth it is said that the isodidact buried the Mendicant Bias under the sands of the Ark. This creature that is rising out of the sand won't be Mendicant Bias but perhaps it's a guardian many speculations point towards the forerunner structures known as seekers.

Now as to how could the chief reach the ark.

Well in [ Register or Signin to view external links. ] [ Register or Signin to view external links. ] it clearly shows that humans have been back to the ark.

Now why would the chief want to find Mendicant Bias.

Well if you didn't know by know it was Mendicant Bias who sent chief to requiem most likely hoping that the Didact will help humanity as was his mission in life to help humans attain the Mantle of Responsibility but as he was never given the Janus key the librarian already knew he wasn't going to help humanity.

Janus key.

The Janus key was given to Halsey from the librarian The Librarian told Catherine to take the key to the Absolute Record. It is believed that Mendicant Bias is the only known A.I who knows the location of the Absolute record.

Do you believe this stuff has anything to do with halo 5 will add more stuff when i can think of it i'm quite sure i forgot alot of the stuff i wanted to put in will update later