Nine beaches in Sydney, including well-known Manly beach, were closed to bathers on Tuesday after small white and grey balls of debris washed up on the shores at the height of the summer holiday season.

Sydney’s popular Manly Beach and other beaches around the Australian city were closed on Tuesday as authorities investigated marble-sized balls of white and gray debris that had washed on shore, in the latest such mysterious incident in recent months.

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.