Actually, I re-watched a programme from the late 90's on this very subject... at that time, the debate about the validity of the initial findings was still undecided but I think since then it's been proven that the bacteria were Earth-related.

If I remember rightly, the meteorite was blown off Mars by an impact several million years ago and struck the Earth about 4,000 years ago. But how they were able to date this, I don't know LOL

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"The stars are my home"
"I've seen things you people wouldn't believe... Attack ships on fire off the shoulder of Orion... I've watched c-beams glitter in the dark, near the Tanhauser Gate... all those moments will be lost, in time... like tears in the rain..."