Almost every guide claims that one can seal a jar indefinitely provided the correct ratio of flora, substrate, and microfauna is achieved. From a thermodynamic and biochemical standpoint, this is fundamentally absurd. A closed system lacking an active sink for metabolic waste or periodic mineral replenishment inevitably trends toward systemic failure. Your moss is not 'thriving' three years in; it is merely surviving on an increasingly constrained nitrogen loop and degraded light transmission through internal microbial films. If you never open the seal to vent volatile compounds and replace trace nutrients, you are managing a delayed anaerobic decay experiment, not an ecosystem.