Marimo Cladophora ball.
マリモ 毬藻. Lake ball, moss ball (Aegagropila linnaei)
Place of origin : Northern Hemisphere including Japan and Iceland . What looks like a large green sphere is actually a collection of small algae with a thickness of 0.05 to 0.1 mm and a length of 0.5 to 3.5 cm. Each individual is a dark green filament, which was originally attached to pebbles or rocks, but was torn off by something and entwined with each other to form a group. In Japan, it is distributed mainly in cold regions such as Hokkaido and Aomori prefecture, and inhabits shallow lake bottoms with a depth of 2 to 3 m where light reaches. Among them, the one in Churui Bay on the north side of Lake Akan is a big size with a diameter of 20 to 30 cm. It can be seen overseas in northern Europe, Russia, North America, etc., but it is said that the velvety large spherical marimo grows only in Lake Akan in the world. In recent years, the number of individuals has decreased due to water pollution and fluctuations in water level, so the marimo of Lake Akan is a national special natural monument, the marimo of Fuji Five Lakes is a natural monument of Yamanashi prefecture, and all domestic monuments. Marimo is designated as Endangered Class I.