Containing bacteria, algae, and tiny shrimp, the Museum’s ecosphere was sealed in 1999 and hasn’t been opened since: it’s a self-sustaining habitat. How does it work? Algae make food from sunlight. Shrimp take oxygen from the water and exhale carbon dioxide; algae take in CO2 and give off O2. Microbes feed the shrimp—and the CO2-rich shrimp poop helps the algae and microbes! The idea of a closed, self-sustaining ecosystem shouldn’t be too strange, because you’re living in one: Earth. See the ecosphere in the Hall of the Universe.