A self-contained, self-supporting ecological system is permanently sealed within this hand-blown borsilica glass sphere. Its careful balance of air, water, plant and animal life was developed as the result of years of NASA research into self-sustaining, bio-regenerative systems where the equilibrium must be maintained for long periods of time, such as long-term space stations. Inside, tiny shrimp feed on bacteria that metabolize organic waste into nutrients for the algae which, in turn, photosynthesize the oxygen needed for the shrimp and bacteria to survive. The life span of the shrimp is up to three years and that of the algae and bacteria is indefinite. 5 1/4" diameter. Available only in the Continental U.S. Premium or Express delivery is not available for this item.