The small balls that washed up on several Sydney beaches last week and led to their closure were found to contain dangerous and toxic substances.

Analysis showed the balls contained saturated fatty acids, E. coli (ie coliform bacteria) and faecal bacteria. They also contain pumice from volcanic rock.

Nine beaches, including the popular Manly and D-Wye beaches, were closed on January 14 after glass marble-sized balls began washing up. It is a reminder that it is mid-summer in Australia and the beaches are visited by thousands of people.

Authorities are urging people not to pick up the balls and to notify officials as soon as they find them, the BBC reports.

In October, thousands of black balls had appeared on the city’s shores, forcing authorities to close some of its most famous beaches for several days and order a clean-up.

The investigation found everything from cooking oil and soap particles to blood pressure medication, pesticides, hair, methamphetamine and veterinary drugs.