The self-contained ecosystem flourished for more than 60 years as a perfectly balanced garden and self-sufficient ecosystem.
The bacteria in the compost ate the dead plants and broke down the oxygen released, turning it into carbon dioxide, essentially forming a microcosm of Earth.
For teachers: This is a great project at the end of the year. It doesn't have to be this big, and it can even be a sealed aquarium (terrarium). Next Fall you can invite your former students to stop in to see it. To add a little more excitement, many types of insects, spiders, worms, snails and even flies can survive in a closed terrarium. Springtails, earthworms and woodlice are found in most closed terrariums.