"Years. It takes years. They're effectively sterile, so they don't decompose - they disintegrate over time. They eat&mdash" again that unbearable composure—"but they don't digest what they eat. Some theorise that they consume themselves over time, or that the virus somehow photosynthesises to drive its host. But we don't know.

"The only way to stop them is to cut off the control centre - to destroy the brain - but, billions of them across the world. And there are always new reservoirs of the virus. It's not good, Sayu."

Classic, classic understatement.