[ptrtarget]

"See, there's mites around all the time. They use sparkles to talk to each other," Harv explained. "They're in the food and water, everywhere. And there's rules that these mites are supposed to follow. They're supposed to break down into safe pieces... But there are people who break those rules [so the] Protocol Enforcement guys make a mite to go out and find that mite and kill it. This dust - we call it toner - is actually the dead bodies of all those mites.

Toner: dead bits of nanomachines. From The Diamond Age, by Neal Stephenson.