Marimo balls also known as Aegagropila linnaei are green algae balls that are found in freshwater lakes in the northern hemisphere. They are compatible with most of the aquatic pets and just need to be submerged in water to live. When they arrive, give them a gentle wash before putting in the water. Marimos make perfect plant pets for Children due to easy care. Marimo balls thrive without much light in freshwater containers. We recommend putting Marimo balls in your aquarium or a glass jar with fresh water. Remember to change the water every 2 weeks to keep the Marimos thriving! If the Marimo balls start getting brown spots, they are getting too much light! Bulk Pack Marimo Balls Marimo Ball: 1-2" inches diameter Shipping: We ship these damp in a sealed bag.