Australia's most famous sight crumbles

After withstanding the pounding of the sea for an estimated 6,000 years, the 45-metre (150 yard) rock pile tumbled into a collection of rocks and debris on Sunday morning before a bewildered Sydney family.

The collapse was accompanied by a noise compared to a loud wave.

"They said it sort of shimmered or shuddered and then fractured and collapsed straight down on itself -- it was almost like a building demolition," a spokesman for Parks Victoria told the Daily Telegraph.

"All that remains now is quite a substantial pile of rubble, about 10 metres above sea level."

The collapsed pillar was one of the bigger rock formations and "integral to what used to be the view," he added.

The Twelve Apostles are giant rock stacks of varying heights in the Southern Ocean which began forming 20 million years ago when erosion gradually began whittling away the limestone cliffs of Port Campbell.