Thousands of living green balls have taken up residence on an Australian beach
Image: Screenshot, 7News report

Last weekend, thousands of peculiar green balls appeared on Dee Why Beach near Sydney in Australia. About 6 centimetres in diameter, these squishy little spheres are living organisms - seaweed balls known as ‘marimo'.

"They're actually a really unusual growth form of seaweed, because seaweeds mostly grow on the rocks but occasionally they get knocked off and rolled around in the ocean forming these beautiful little balls,” Alistair Poore from the University of New South Wales explained to 7News."It's quite an unusual phenomenon, it's only been seen a handful of times around the world.”

First discovered in the 1820s by Austrian botanist Anton Eleutherius Sauter, and named by Japanese botanist Tatsuhiko Kawakami in 1898 ("marimo" roughly means "bouncy play ball” in Japanese), colonies of these little balls have only been seen off the coast of Iceland, Scotland, Japan, Estonia and now Australia. According to Rachel Nuwer at Smithsonian Magazine, in Iceland, the balls have been given a less adorable nickname, referred to as kúluskítur or “ball muck”.

I suppose no one will be surprised when I say that in Japan, as well as being a natural phenomenon, marimo are a beloved ‘pet’. Here's a whole tankful: