Three days after discovering Taumoeba in his fuel line, Ryland Grace isolates each fuel tank, tests samples, and confirms all nine are uncontaminated. He restores thrust to 1.5 g and builds a simple “Taumoeba alarm” using an Astrophage slide and light sensor to detect future outbreaks.

Grace methodically tests possible sources. Mini-farms intended for the beetles show no leaks, and additional tests around installed beetles John and Paul also come up clean. He seals breeder farms in bins with Astrophage slides and sleeps nearby to monitor results.

By morning, every breeder farm’s slide is clear—proof Taumoeba escaped—yet his lab alarm remains dark, and farm readouts still show healthy populations. Puzzled, Grace reasons that nitrogen would have killed the Taumoeba if a crack existed, and he hypothesizes the organisms are traversing xenonite at the molecular level.

To test this, he fabricates xenonite and plastic “sandwich” samples containing sealed Astrophage, then exposes one set to natural Taumoeba and the other to his engineered, nitrogen-tolerant strain (Taumoeba-82.5). Results show Taumoeba-82.5 can penetrate xenonite but not plastic/epoxy; natural Taumoeba cannot penetrate either. He realizes he unintentionally bred a strain adapted to survive nitrogen by retreating into xenonite itself.

Grace decides to rebuild the farms with metal casings, confident the strain remains viable for Venus and Threeworld. Then a chilling implication hits: Rocky carries the same strain in xenonite farms aboard a ship whose critical bulkheads and fuel tanks are xenonite, putting Rocky’s Astrophage supply—and life—at risk.