Lake Akan is home to these velvety soft spheres of algae. Marimo are related to similar species found in Europe and other parts of Japan but they only grow to 20 or 30 centimeters in this lake. They were almost driven to extinction by habitat destruction (the lake is a water source for the town and a tourist attraction). Then in 1920 a hydroelectric plant was built along the Akan river which flows into the lake. The resulting drop in the water line exposed many of the marimo which whithered and died. In 1921 the marimo became a national treasure and visitors came and took many as souvenirs or for resale in other parts of the country. In the 1940's the locals set out to protect this unique plant and in 1950 the first Marimo festival took place.