alt Hacker News> to build stable closed ecosystems
Sealed terrariums? Unless you mean something more complex than plants, soil, sunlight, and water?
https://laidbackgardener.blog/2019/10/14/the-worlds-second-o...
"That means it has been growing inside its bottle with no additional air, water or fertilizer for 47 years."
I don't think that terrarium contains any animals.
The 'biosphere 2' attempt at building a self-sustaining environment with humans, did not succeed.
https://en.wikipedia.org/wiki/Biosphere_2