Cladophora aegagropila is not really a plant, but a ball of algae 3-10 cm wide. It is a decorative exception to the rule of avoiding algae. It is found in shallow lakes, where wave movement shapes them into spheres. In an aquarium, it should be rotated regularly to maintain its shape.

• It can be divided into smaller pieces, which become spherical over time.
• It can form a carpet if tied to roots and stones.
• Protected in areas of Japan.