published as an article in "Science" a few days later. Under a scanning electron microscope, structures were visible that some scientists interpreted as fossils of bacteria-like lifeforms. The structures found on ALH84001 are in diameter, similar in size to theoretical nanobacteria, but smaller than any cellular life known at the time of their discovery. If the structures had been fossilized lifeforms, as was proposed by the so-called biogenic hypothesis of their formation, they would have been the first solid evidence of the existence of extraterrestrial life, aside from the chance of their origin being terrestrial contamination.