A cross-referenced identification record compiles what's known of the entity researchers have designated Zoo Keepers. An emergence process, a settled form, and a method of contact no subject has survived to fully explain.

Five of us went down. The hull was a cylinder, not a sphere — cheaper to build that way, worse to hold pressure that way, though nobody said the second part out loud. At 900 meters, the first sound came through the hull. It wasn't the hull that was listening back.