Many grim-looking (and smelling) balls washed up on the beaches of Sydney, Australia in October. First believed to be balls of tar, further analysis and chemical tests have revealed them to be far more disgusting than that.

Last month, eight beaches in Sydney, including the famous Bondi Beach, had to be closed in order to clean up the mystery globs and for authorities to investigate their source. 

The initial analysis made for pretty grim reading.

“Based on advice from the Environment Protection Authority, we can now confirm the balls are made up of fatty acids, chemicals consistent with those found in cleaning and cosmetic products, mixed with some fuel oil,” New South Wales Maritime Executive Director Mark Hutchings told the BBC as the beaches reopened in mid-October.

Waste from an oil spill was suspected as the ultimate cause. However, further analysis of the globs of miscellaneous waste – including carbon-14 dating, mass spectrometry, elemental analysis, and microscopy techniques – has determined they contain traces of cooking oil, soap scum, hair, human fecal matter, veterinary drugs, blood pressure medication, PFAS (aka “forever chemicals”), and the psychoactive substances THC and methamphetamine. 

“They smell absolutely disgusting, they smell worse than anything you’ve ever smelt,” Analytical Chemist Professor William Alexander Donald told 9News. “I wouldn’t want to be swimming with them,” 

The balls’ composition suggests they likely came from sewage or some other kind of urban effluent, though the exact source is still unknown. If you should happen upon one though, it’s probably best not to touch it.