Red rain came from Mars via comet.
Wikipedia article
http://en.wikipedia.org/wiki/Red_rain_in_Kerala
describes red rainfalls that occurred in 2001 in Kerala, India.
I found numerous mammalian red blood cell fossils in the following micrographs of the red rain particles:
Edit [Moderator]: Link removed
Edit [Moderator]: Link removed
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Only mammals possess this unique kind of red blood cells. Since Mars and Earth are the only two planets in our solar system that have ever been inhabited by mammals, the red rain in Kerala, India should have originated from Mars via a comet.