A tiny crystal thought to be the oldest object on Earth has gone on public display for one day only in the US state of Wisconsin.
The zircon grain is barely two human hairs in diameter
The 4.4-billion-year-old zircon crystal, barely two human hairs wide, was brought out at the University of Wisconsin-Madison on Saturday.
The day's festivities also featured the Rock Concert, which was to include jazz from a band using rocks as percussion.
The zircon, found in Australia in 2001, led to a reappraisal of early Earth.
Analytical work by geophysicist Professor John Valley at the university in Madison, Wisconsin, showed the crystal could only have formed in a low-temperature environment.
That suggested the early Earth was much cooler than previously thought, meaning life-forming elements such as oceans were formed earlier, too.
Saturday's accompanying music included jazz composed especially for the day to try to answer the question of what 4.4 billion years old sounds like.
Roy Nathanson, who composes for the performing New York-based Jazz Passengers, said his rock banging, jazz and computer beats would trace the crystal's origins.
"The whole thing is something that captures your imagination," he told the Associated Press news agency.
Professor Valley said: "This is our first glimpse into the earliest history of the Earth. The miraculous thing about the crystal is that we've been able to make such wide-ranging inferences about the early Earth."
The festivities also included a lecture from the man who decided the age of the crystal - Professor Simon Wilde of the Curtin University of Technology in Perth, Western Australia.