Seventh Column

The Seventh Column is a hollow ring with seven rectangular spokes. The one on the top goes into the middle and is not connected to the rest of the ring.

Meaning of the symbol
The Seventh Column represents Bungie's entertaining step to world domination. Each spoke resembles a purpose. They are listed as so:
 * 1) Start independent gaming software company. (Completed)
 * 2) Dominate Mac platform: Launch assault on Windows platform. (Completed)
 * 3) Announce killer gaming title. (Completed)
 * 4) Acquire strangely addictive Chinese food company. (Completed)
 * 5) Recover Ling Ling's head. (Completed)
 * 6) Stage bloody coup of new parent company. (Completed)
 * 7) Take over World. Shoot enemies into sun with giant slingshot. (In progress)

You can find these steps in the extra disk that comes in the Halo 3 Legendary edition. If you look closely, some of the wall mounted computer monitors in "Crows Nest" have white Seventh Column symbols among the contact icons. In Halo 3 the seventh column is on UNSC pilots' helmets.

This is possibly the reason for Bungie including the number 7 in many of their games.