Cladophora aegagropila is not actually a plant, but a ball of algae 3-10 cm wide. It is a decorative exception to the rule of avoiding algae at all costs. It is found in shallow lakes, where the movement of the waves shapes it into a sphere.

In an aquarium, it should be turned regularly to maintain its shape. Cladophora aegagropila can be divided into smaller pieces, which become spherical over time, or which form a mat if tied to roots and stones.

Protected in areas of Japan.