Nano marimo (with Apple glass and glass sand) Marimo balls are considered a treasure in Japan and that's why it's featured on many items in Japan. The Marimo Moss Ball is so popular because it's simple to raise and keep in a pond or aquarium. You can keep these in little table aquariums all the way up to the biggest fish tank you can get. Their is no special way to care for the moss balls or a tank requirement. You don't need fertilizer which is great and any light will do for them unlike most plants that require special lighting requirements. The third thing that makes Marimo Moss Ball so interesting is the ability to float and sink freely. What is so popular about Marimo ? 1. It's petite appearance， make it evergreen in an aquarium and glass bowls. 2. It requires no feeding， no special lighting， normal room temperature， no heating required. 3. It is alive， it swims， it grows， it gives birth to babies across time. 4. It's maintenance free， make it an ideal pet for modern busy lifestyle. 5. It can be kept together with fishes in your pretty aquarium 6. It can be kept at home， in the offices. A great decorative item for any venues. 7. It is light weight and you can bring it with you anywhere for traveling.