One Ring stood alone, unwatched.
Like the others, it grew slowly. It began as a crater and ejection zone. Over years its base formed by the nearly imperceptible movements of nearly invisible machines. Then the arc of the Ring itself emerged. The arms extended to make a circle that would reach a half mile in diameter.
Like the others, it was close to completion and ready to achieve its purpose. But it was patient. It spoke to the others by means unknown to what remained of human civilization and they coordinated. Their growth would end and something new would begin.