Sort of habitat in a bottle garden

CLOSEDECOSYSTEM

Think of a self-sustaining miniature world where plants and microorganisms recycle air and water without outside help—like a sealed glass jar. The name describes its isolated, balanced nature.

A "bottle garden" is a self-contained plant environment, which fits the idea of a "closed ecosystem"—a system where plants, soil, and moisture recycle without outside input. The clue hints at this by describing a "sort of habitat" (ecosystem) that’s enclosed (closed) in a bottle. The answer combines "closed" and "ecosystem" directly, with no wordplay or hidden tricks.