his semi enclosed ecosystem is perfect for desk decorations, no maintenance needed. It's a well design balanced ecosystem. Inside, there are 6+2 Halocaridina rubra shrimp, multiple types of algae and microorganisms that break down waste and convert it to algae food, in turn, the algae produces oxygen and food for your shrimp. These shrimp can live up to 15-20 years. Entertaining to watch. Especially great for people who can't have large pets, students in dormitory/apartments, and kids who wants to learn about symbiotic self sustaining ecosystems. Please keep the cork closed, do not add food or other fish or decorations.