Aegagropila linnaei - “Marimo Moss Balls”
Syn. Cladophora aegagropila

Aegagropila linnaei or Moss Ball is a rare form of algae found in shallow lakes where it tubles along the bottom of the lake to form its spherical shape. 

Light: Keep your marimo where they will receive low to medium indirect light. You must protect marimo from the direct rays of the sun, as marimo can easily turn brown if they are getting too much sunlight. 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.

Water: Change their water once every week using distilled, regular tap water (using water that has sat out 24-48 hours will cause less shock than water straight from the tap). You’ll need to change the water more often in summer, as the heat will cause more evaporation. Clean your marimo enclosure with a brush if algae begins to grow on tank surface. Lightly squeeze the old water from your marimo ball when changing. 

Environment: Marimo is a type of green algae found primarily in the lakes of the northern hemisphere. A marimo is a rare growth form of the algae, and colonies of balls have been found to develop in Iceland, Scotland, Japan, and Estonia.  

Toxicity: Not available, advised not to consume.

Of Note:

  • If your marimo turn brown, make sure they’re moved to a cooler location with less direct light. 
  • Marimo are not actually moss, but algae.
  • Despite the common Japanese name, they were first discovered in the 1820s in Austria.
  • In Japan, some of the marimo colonies are in decline for unknown reasons. They have been listed as a protected species in Japan since 1920, and defined as a natural treasure.