UFO or alien eggs? Hundreds of mysterious green, sponge-like balls have been washed ashore in a northern Sydney beach.
UFO or alien eggs? Hundreds of mysterious green, sponge-like balls have been washed ashore in a northern Sydney beach.Twitter ScreenShot/ @OddNews

Hundreds of mysterious green, sponge-like balls that have been washed ashore a northern Sydney beach have stunned surfers and beachgoers.

The unidentified floating objects that have appeared in Dee Why's beach have prompted questions among locals if the green furry balls are alien eggs, Japanese moss balls or some kind of 'tennis nightmare'.

"I didn't want to touch one because you never know what can sting you on the beach, but I did poke it with my toes and it's squishy, like a sponge," the beach's Life Saving Club patrol member Rae-Maree Hutton told Manly Daily.

"They look like alien eggs or something".

Another local resident Jenny Zhang told the publication that she walked the seashore every day and had never come across anything like it ever before.

"About three days ago, there were a few egg-shaped balls but then today, they were much bigger and everywhere on the beach," she said adding: "I tried to search on the internet but there was no information. They look like Japanese moss balls but they're not made of moss, maybe seaweed."

Scarlett de Villers from nearby Davidson saw the grotesque balls during her regular morning walk alongside the beach.

"I picked one up and squeezed it and it was so squishy – but i wan't sure if it was laive and was worried I might hurt anything inside," she told the Daily Mail. "It struck me how perfectly shaped they all were and how green and alive they looked."

Scientists, at the moment, don't seem to have a definitive answer to what the weird balls are.

Associate Professor Alistair Poore from the School of Biological, Earth and Environmental Sciences at the University of NSW said the spear objects could be a rare type of living green algae, which has been seen only a few times around the world.

"I've seen similar things – sometimes dead sea grass can roll around and form balls like underwater tumbleweeds but that's made of dead material and these look to be living," he told the Manly Daily.

"It is a habit known as 'aegagropilious', where the algae is free living (not on rocks) and forms into spherical balls."