Man made sonsohfatfish said:These are marimo moss balls and no they are not man made. They are formed by the constant rolling on the bottom of Lake Akan in Japan due to under water currents. Marimo balls are supposedly able to rise and sink in response to columns of light due to photosynthesis. They need temperatures below 25 degrees to thrive. Rinsing the ball occasionally with running water and rolling it between your palms will keep the ball in a spherical shape.