There have been some fairly odd beachgoers at Dee Why Beach outside of Sydney, Australia lately: thousands of small, green balls that are actually alive. These soft orbs, about six centimeters in diameter, are actually a form of algae (Aegagropila linnaei) called marimo. Previously, marimo balls have been been found in Japan, Iceland, and Scotland, so their appearance in Australia is quite peculiar.
The algae can grow on rocks or be free floating filaments that coat the floor, but forms the ball shape under certain circumstances. The balls do not have a core, and they have been seen growing up to 30 centimeters in diameter.
These balls actually make fantastic pets, since they only need light for photosynthesis and clean water to thrive. Rotating them in the tank allows them to stay round and green all over.
