Apparently the CI chondrites class of meteorites are rare, all having fallen within around 200 years (oldest find in 1806). http://en.wikipedia.org/wiki/CI_cho

Apparently the CI chondrites class of meteorites are rare, all having fallen within around 200 years (oldest find in 1806). http://en.wikipedia.org/wiki/CI_chondrite http://en.wikipedia.org/wiki/CI_chondrite Even assuming the possibility of bacteria contagion from Earth the question remains how the biological remain appears to contain no nitrogen, an essential building block to life as we know it.