True. I got visions of patches of moss growing on the outside of the ISS

Haha, It reminds me some old movie called Andromeda I think... Space human probe crashlanded on earth and contained some greenish patches of stuff on it. It was space dwelling orgamism that direcly used energy to matter conversion for growth. It was pretty decent movie actually :)

Andromeda Strain, Michael Crichton's first big success.

Great movie, but even better book.