Fossil mounds may be oldest life on Earth

Odd-shaped mounds of dirt in Australia turn out to be fossils of the oldest life on Earth, created by billions of microbes more than 3 billion years ago, scientists say in a new report.

And these mounds are exactly the type of life astrobiologists are looking for on Mars and elsewhere.

A study published Thursday in the journal Nature gives the strongest evidence yet that the mounds dotting a large swath of western Australia are Earth's oldest fossils. The theory is that these are not merely dirt piles that formed randomly into odd shapes, but that ancient microbes burrowed in and built them.