A NASA scientist claims to have found microscopic fossils of alien life among fragments of a meteorite.
Space agency boffin Richard Hoover has published pictures of the fossilised, worm-like bacteria in a paper (opens in new tab) for the peer-reviewed Journal of Cosmology.
Hoover calls the creatures "indigenous fossils", claiming that they originate beyond the Earth, and have were not introduced after the meteorite landed.
The fossils come from fragments of carbonaceous 'chondrite' meteorite, which was sliced apart and examined using a powerful electron microscope. This type of meterorite is rare - only nine examples are known to have fallen to earth - but contains high levels of water and organic material.
According to the study, "these fossilized bacteria are not Earthly contaminants but are the fossilized remains of living organisms which lived in the parent bodies of these meteors, e.g. comets, moons, and other astral bodies."
"The implications are that life is everywhere, and that life on Earth may have come from other planets."
This isn't the first time that scientists have alleged that evidence of extra-terrestrial life has been contained within meteorites, and earlier studies have aroused a certain amount of scepticism within the scientific community.
The Journal of Cosmology's editor-in-chief, Rudy Schild of the Center for Astrophysics, Harvard-Smithsonian, was keen to emphasise the credentials of this most recent study, however, describing Hoover as a "highly respected scientist and astrobiologist with a prestigious record of accomplishment at NASA."
"Given the controversial nature of his discovery, we have invited 100 experts and have issued a general invitation to over 5,000 scientists from the scientific community to review the paper and to offer their critical analysis," he said.
Schild says that the comments of these peer reviewers' comments will be published between 7th and 10th March.
The study follows an earlier report last year, in which NASA scientists claimed to have found a new kind of lifeform (opens in new tab) that is not composed of the same building blocks as all other life on Earth - renewing speculation about the wider possibilities for life on other planets.