Authorities have been confounded by an unknown metal object that washed up on Green Head beach, about 250km (155 miles) north of Perth in Western Australia.
Officials and investigators are looking into the matter and appears to be a part of some aircraft.
Police termed the mysterious object hazardous and urged people to keep a safe distance from it.
Police said in a statement: “We want to reassure the community that we are actively engaged in a collaborative effort with various State and Federal agencies to determine the object’s origin and nature.”
According to Australian media, Green Head beach residents said the cylinder was about 2.5m wide and between 2.5m and 3m long.
ABC reported that residents visited the site Saturday night to see the cylinder with one local describing it as a “great social evening”.
“It was a lovely, still night, the kids were digging sand castles around it,” he told the ABC.
Geoffrey Thomas, an aviation expert said the item was possibly a fuel tank from a rocket that had fallen into the Indian Ocean at some stage in the past 12 months.
It was possible the giant cylinder could have fallen from a “foreign space launch vehicle” and it would liaise with other international agencies, the Australian space agency stated.
While there was some speculation the cylinder may have been a part of MH370 — an aircraft with 239 passengers which went missing off the west Australian coast in 2014 — Thomas said there was “no chance”.
“It’s not any part of a Boeing 777 and the fact is MH370 was lost nine and a half years ago so it would show a great deal more wear and tear on the debris,” he said.