The two-inch wide lump of space rock, that fell in central Sri Lanka in December, is pitted with microscopic seaweed fossils similar to those found on Earth, said Professor Chandra Wickramasinghe, former head of Cardiff University's Centre for Astrobiology.
"These finds are crushing evidence that human life started from outside our Earth," said Wickramasinghe, who is controversial for his theories that life on Earth 'seeded' from the outer space, the 'Daily Mail' reported.
"We are all aliens - we share a cosmic ancestry. Each time a new planetary system forms a few surviving microbes find their way into comets," he said.
"These then multiply and seed other planets. These latest finds are just more evidence to point to the overwhelming fact that life on Earth began on other worlds.
"Our provisional assessment is that it was part of a comet," Wickramasinghe said.
"The stones look extremely unusual, and have a porous structure, with a lower density than anything we have on Earth," he said.
Wickramasinghe's claims are outlined in a freely accessible paper on the website of the Journal of Cosmology.
It says "a few per cent carbon as revealed by analysis confirms the status of a carbonaceous meteorite".
However, he admits that key tests to prove the rock is an uncontaminated meteorite are yet to have been carried out.
However, many experts have already dismissed his claims as "laughable" and argued that the apparent extra-terrestrial fossils are clearly present as the result of contamination on Earth.
They point out that it has yet to be proven that the rock is actually from space at all.
Wickramasinghe's research alleges that "microscopic fossilised diatoms (a basic form of algae) were found in the sample".
The finding, it suggests, is a "strong evidence to support the theory of cometary panspermia" - the idea that life across planets is spread on rocks hurtling through space.
The still-smoking meteorite fragments were picked up by villagers in central Sri Lanka after they crashed to Earth in a spectacular fireball, it is claimed.
They were analysed in a British laboratory where fossils of algae were apparently found, the report said.
"The algae organisms are similar to ones found in Earth fossils but the rock also has other organisms we have not identified," Wickramasinghe said.
