A MICROSCOPIC, single-cell fossil found in a meteorite that fell to Earth in a Sri Lankan village late last year proves that extraterrestrial life exists, scientists claim.

The discovery of fossil diatoms (a group of algae) in the meteorite could answer one of humankind’s burning questions : are we alone in the universe?

In a paper published last week in the Journal of Cosmology, a scientist at the University of Buckingham, in the UK, claimed to have compelling evidence that there is other life out there.

The lead scientist on the paper, the director of the university’s Centre for Astrobiology, Prof Chandra Wickramasinghe, was the co-developer of the theory of panspermia, which holds that life exists across the universe and is spread by asteroids and meteoroids.

The paper, Fossil Diatoms in a New Carbinaceous Meteorite, said the discovery of a fossil in the space debris that fell to Earth provided "strong evidence" to support the theory.

The director of the Institute of Human Evolution at Wits University, Prof Francis Thackeray, said on Tuesday that the report, while likely to be "very controversial", was also "very exciting".

He said space agency Nasa’s research on samples from Martian meteorites that fell to Earth pointed to the possibility of life on the red planet. But this was rejected amid fears that the samples had been contaminated on Earth.

Samples taken on Mars by the Phoenix Lander in 2008 found water, carbonates and perchlorate, all crucial to life, but Prof Thackeray said there was "no consensus" among scientists and the topic was "very controversial".

He said the Sri Lankan meteorite find was exciting because the rock did not come from Mars.

Describing a tiny fossil in the meteorite seen through an electron microscope, the paper said it had a microstructure and morphology characteristic of "a wide class of terrestrial diatoms" — unicellular phytoplankton.

"The intricately woven microstructure of these frustules (cell walls) would be impossible to generate abiotically (in the absence of life), so the presence of structures of this kind in any extraterrestrial setting could be construed as unequivocal proof of biology."