Are Aliens Among Us?

From Scientific American:

If, as many scientists believe, life can readily emerge under the right environmental conditions, it is possible that life arose on Earth more than once. Researchers are now seeking evidence of a second genesis by searching for exotic microbes that are biochemically different from all known organisms. In this image, artist Adam Questell has imagined an alien cell that carries its genetic material in twin nuclei.

Cell_2

More here.