In 1864 a strange type of rock fell from the sky above Orgueil in rural France. Shocked and frightened locals collected pieces of the peculiar, peaty blob from the surrounding fields, and passed them on to museums and scientists.

At that time, a debate had been raging over the origin of life; Could life possibly form from mere chemicals? Or did it need some strange unidentified vital substance?

Into this debate fell the Orgueil meteorite, and because it seemed remarkably similar to loamy soil, some wondered whether it may hint at the existence of extra-terrestrial life.

The great Pasteur allegedly investigated, but disappointingly found no such thing. Nevertheless, the mere possibility prompted later ideas that the origin of life on earth indeed lay elsewhere in the universe, ideas that were greeted with varying degrees of scepticism over ensuing decades.

As Phil Ball narrates, given how much was at stake, and how bitterly scientists argued on either side, the most remarkable thing about the story is the extraordinary secret the meteorite kept to itself until exactly 100 years later.

Producer: Alex Mansfield

Image: These faint shapes found in meteorite AH844001 found in Antarctica were, until quite recently, thought by some to be alien fossils. But thoughts of extra-terrestrial life being carried in such meteorites goes back at least as far as 19th century France. BBC Copyright