Forerunner WoMD 1

Each Halo was about thirty thousand kilometers in diameter, a slender ribbon tied up in a perfect circle, the outer surface acquiring detail as we grew closer and as the sun’s light angled to create deeper shadows. The inside of the nearest ribbon was strangely mottled, partly green, partly blue—but mostly bluish silver. As well, I could now make out waves of hard light rippling around the inner surface, occasionally shooting slender spikes toward the axis—then withdrawing them, as if trying unsuccessfully to spin out the spokes of a vast wheel.

Mendicant Bias has exceeded its present ability. It can control only five installations out of twelve. The others will maneuver to save themselves. They will attempt to access the portal.
(Halo:Cryptum; Ch.37)