Marimo moss ball

Moss Balls are a species of filamentous green algae (Chlorophyta) found mostly in a number of lakes in the northern hemisphere. A marimo is a rare growth form of the species where the algae grow into large green balls with a velvety appearance. They can grow patches on a lake floor at depths from 2 to 2.5 m. The round shape of the marimo is maintained by wave action that turns it.
In Japan the marimo has said to be a national treasure. They where named by the Japanese botanist "Tatsuhiko Kawakami". Mari means bouncy ball and Mo is a term for plants that grow in water. So , marimo means bouncy plant.  People often mistake them for living animals because they are usually moving around in the tank. Basic Care Tips