Months after a mysterious black ball forced the closure of some of Sydney’s most famous beaches, small marble-like fragments are starting to wash up on the city’s shores again.

The balls – this time gray or white – prompted the council to close nine beaches, including the popular Manly and Dee Why beaches, while authorities investigated.

Eight beaches, including Bondi, were closed for several days in October and the government ordered a massive clean-up after thousands of black deposits began to appear on the coast.

Testing by authorities determined the balls were likely the result of a sewage leak.

Northern Beaches Mayor Sue Hines said the latest ball “could be anything”, Guardian Australia reported.

“We currently don’t know what it is, which makes it even more concerning,” she said.

“Something was obviously leaking or falling out… floating in there and being tossed around.”

Northern Beaches Council posted on Facebook on Tuesday that the NSW Environmental Protection Agency (EPA) had alerted them about the new debris.

The agency and committee plan to collect the findings for testing and examine other beaches in the area.

The committee added that anyone who finds the balls should contact authorities.

While widely reported as “tar balls,” the October debris was later found to contain everything from cooking oil and soap scum molecules to blood pressure medications, pesticides, hair, methamphetamine and veterinary drugs.

Scientists say they resemble clumps of fat, oil and grease (commonly known as fat clumps) that often form in sewage treatment systems.

However, Sydney Water reports there are no known issues with the city’s waste system and authorities still don’t know the source of the material, prompting some to raise concerns about the safety of the city’s beaches.

State politician Sue Higginson, from the Green Party, said in a statement in December: “The EPA cannot explain the source of the human waste that causes the fatbergs or reassure the public that Sydney’s beaches are safe to use. ”