Halo 3 Easter Egg - Marathon symbol on Heretic

Start up your Halo 3 multiplayer disk that came with Halo 3: ODST and go to the level Heretic. Depending on which base you start in, look left if you were looking TOWARDS the red base from the Blue base, or right if looking AWAY from red base towards blue base to see a Marathon symbol reflection on a wall. You can tell which base your looking at or are in by looking at the outline of the main "Window" that overlooks the middle of the area.