Marimo is a rare growth form of Aegagropila linnaei in which the algae grow into large green balls with a velvety appearance. The species can be found in a number of lakes and rivers in Japan and Northern Europe. Colonies of marimo balls are known to form in Japan and Iceland, but their population has been declining.
Keep your Marimo where they will receive low to medium indirect light. You must protect marimo from direct sun, as Marimo can easily turn brown if they are getting direct light! Also keep in mind that direct sun will be intensified by glass marimo enclosures which can heat water quite quickly. Remember - these guys are native to cool lakes, and should be kept cool.
Marimo are well adapted to low light spaces and can photosynthesize in normal household light. If your space has no window, keep marimo close to a fluorescent or full-spectrum bulb.
Changing the Water
Change water once every two weeks using regular tap water (for best results, allow water to sit out for 24 hours prior to changing the water). You’ll need to change the water more often in summer, as it will heat and evaporate more quickly. Clean your marimo enclosure with a brush if algae begins to grow on tank surface.
Keeping Marimo Shape Round
In their natural habitats, the waves and currents of the lakes gently rotate and roll the Marimo balls along the floor of the lake.
To ensure that Marimo stay keep their round form and don’t flatten out, you’ll want to gently agitate the water in your Marimo enclosure, with the goal that when your Marimo balls settle back to the bottom, they rest on a different side than they had prior. Try to simulate the gentle waves of a lake. *pistils nursery