Border Sections

~1500 years ago, after ocean humans abandoned the eroding atolls

We've found that many of the things we take from the world of light don't last well in the atmosphere. Swarms have begun the habit of leaving these objects on the various border sections to keep them from being damaged. Some of the light-exploring swarms have also ceased returning to the Exchange Layer to make reports, preferring to let the other outer swarms bring the reports. These light swarms then wait in the center of the border sections for the outer swarms to bring further instructions.
We're still a little sad about our swarms no longer returning to the wall. A class of swarms that won't even come to the Exchange Layer adds to this sadness. But it's worth it, if the swarms' constant presence at the boundary layer leads to finding the Singer.