In geology, they are named nanobacteria, nanobes, and nanoarchaea.
Some scientists believe they've found nanobes not only in the human body but also in the deepest oceans, in the steamiest hot springs, and on rocks from outer space.
Nanobes not only look like bacteria, but they also seem to behave like other living things, creating colonies, forming chains, and reproducing.
Uwins of the University of Queensland found evidence of DNA in nanobes her team discovered in Australia, but other factors could have contributed to a false positive reading of DNA, argued some skeptics, such as Harvard paleobiologist Andrew Knoll.
On the other hand, nanobes may be a clue that there are forms of life not as we know it.
Some experts believe the same tiny living organisms - called nanobes - could be lurking below the surface of every rocky planet in our solar system.
Dr Uwins and her team have spent the last two and a half years studying the nanobes, since the initial discovery in 1996.
"There must be transitional stages to life and nanobes might cast light on those.