For One Day Only, World's Oldest Item on Display

To create buzz about an otherwise arcane subject, the University of Wisconsin-Madison showed off a tiny speck of zircon crystal believed to be the oldest known piece of Earth at about 4.4 billion years old.

Saturday's daylong celebration was capped with "The Rock Concert" by jazz musicians who composed music to try to answer the question: What does 4.4 billion years old sound like?

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Though scientists acknowledged there wasn't much to see, spectators used a microscope to check out the tiny grain, which measures less than two human hairs in diameter.

Analysis of the object in 2001 by John Valley, a UW-Madison professor of geology and geophysics, startled researchers around the world by concluding that the early Earth, instead of being a roiling ocean of magma, was cool enough to have oceans and continents - key conditions for life.