How possible is it that the germs that created some of the most interesting species on earth was from another planet? Germs live in every environment on earth. Some are even proven to be very good space travelers. Is it hard to imagine that when the big rock hit the dinosaurs' world 65 million years ago that it kicked up some of our volcano-vent-living bacteria and launched it out of our stratosphere into...say Venus where they now spend their days soaking up the sulfuric vents and volcanos like its a resort?
It's called panspermiation, and it's more likely to happen than not. A popular theory is that the bombardment of asteroids is responsible for bringing Earth its water early in its life. Also, judging from recent fossil records, it's a fact that Earth had life only shortly after the molten ball cooled and water formed. Coincidence?