With the advent of this toy biosphere, sustainable self-sufficiency appeared to be quite easy to create, especially if you didn't care what kind of life was being sustained. It turns out that ecospheres scale up well. A huge commercial Ecosphere can weigh in at 200 liters. But instead of the usual three or four spore-eating shrimp, the giant Ecosphere holds 3,000. It's a tiny moon with its own inhabitants.
More individual lives make the ecosystem more resilient.
The larger an Ecosphere is, the longer it takes to stabilize, and the harder it is to kill it. But once in gear, the collective give and take of a vivisystem takes root and persists.