Epikkriz

Video of this in the game

Exhibit A

Whenever the Gravemind closes his mouth his 'gums' are placed together in order to look like Master Chief's helmet

Exhibit B

..and when the Gravemind opens his mouth again and looks towards the Arbiter, it spreads open and his 'gums' curl up so he looks like the upper and lower pieces of the Arbiter's ceromonial helmet.

Disclaimer: I did not take the pictures or the video used in the making of this post.

This Bandit just wants to know what is going on in his life.