These balls grow to sizes of 12 to 30 cm across, depending on where you find them.
Marimo doesnt grow around a core, such as a pebble.
Surprisingly, the ball is green all through, although light only reaches very short distance into the ball.
Small hand rolled balls of free-floating filaments are sold in shops as souvenirs.
Marimo is also a staple in many Japanese aquariums.
Meanwhile in Lake Myvatn, lake balls are slowly disappearing.
Today, theyre mostly gone.
The disappearance is attributed to pollution because of mining operation in the area that commenced in the 1960s.
With less sunlight, the algae began to die off, exposing more of the lake bottoms loose sediment.
