via wikipedia: “Aegagropila linnaei, known as Marimo (毬藻?, literally “ball seaweed“) in Japanese and as Cladophora ball, Lake ball, or Moss Balls in English, is a species of filamentous green algae (Chlorophyta) found 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. Colonies of such balls are only known to form in Iceland, Scotland, Japan and Estonia.“
Location is Lake Akan in Hokkaid