This summer we tripped to Hokkaido, the Northern most island of Japan. One of the places I would have always liked to visit in Hokkaido was Lake Akan. When we were there, a sign was posted saying, "A brown bear was found a few days ago here. Would you like some bells to carry for your safety?" They live only in Hokkaido in Japan. There are several lakes in Hokkaido, but this one in particular is famous for its peculiar moss ball called “Mari-mo (mari =ball, mo=algae)”.
Inside, it branches out tightly and radially and is covered with hard yet velvety green algae. We bought our son two marimos in a glass jar. They are not natural, but cultured. The man at the store collects some algae, keeps it in a container, and rolls it up until nice and round behind his counter when he has some spare time for his customer. He told us to change the water once a week and roll them between palms from time to time to keep shaped, and they would grow bigger every year. Once I had some marimos myself. One day I found they were broken into some pieces and thought I lost them. According to this man the marimo cannot stay tight in still water but if we roll them they will once again make a round shape. I wish I knew it years ago.