Aegagropila linnaei is a very peculiar little aquarium plant. It is a ball-shaped species of green algae with a velvety surface. This form is rarely found in nature; usually they grow in flatter, carpet-like colonies. The interesting round shape is created by gentle wave action along the substrate. Because they tend to grow extremely slowly, moss balls are very popular for use in Nano Cubes and other small aquariums. Combined with stones and roots they give rise to highly attractive designs and layouts.