Cladophora aegagropila is not really a plant, but a ball of algae. It is a decorative exception from the rule about avoiding algae at all costs. It is normally found in shallow lakes, where the movement of the waves forms it into a sphere. In an aquarium it must be turned regularly to keep it in shape. Cladophora aegagrophila can be divided into smaller pieces, which become spherical with time, or which form a carpet, if attached to roots and stones. Protected in parts of Japan.

These are very popular in shrimp tanks but look stunning in most aquariums.