The discovery of the marble-sized balls comes after a similar incident in October closed Sydney's Bondi Beach, among other tourist hotspots.

Sydney’s iconic beaches are famous worldwide for their golden sand and pristine waters. They attract millions of tourists every year, but this time, they have drawn the attention of researchers and local authorities for an unusual reason.

On Tuesday, January 14, nine beaches in Sydney were closed to swimmers due to mysterious balls washing ashore. Local authorities are already working to determine the origin of these findings. Sydney's ocean beaches,

UNSW School of Chemistry Professor Dr Jon Beves says testing will commence to investigate what the mystery balls shutting down Sydney’s beaches are composed of.