This electron microscope image shows extremely tiny tubular structures that are possible microscopic fossils of bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. http://photojournal.jpl.nasa.gov/catalog/PIA00285

This 4.5 billion-year-old rock, labeled meteorite ALH84001, is one of 10 rocks from Mars in which researchers have found organic carbon compounds that originated on Mars without involvement of life. http://photojournal.jpl.nasa.gov/catalog/PIA00289

This electron microscope image shows egg-shaped structures, some of which may be possible microscopic fossils of Martian origin as discussed by NASA research published in the Aug. 16, 1996. http://photojournal.jpl.nasa.gov/catalog/PIA00286

This electron microscope image shows tubular structures of likely Martian origin. These structures are very similar in size and shape to extremely tiny microfossils found in some Earth rocks. http://photojournal.jpl.nasa.gov/catalog/PIA00287

In the center of this electron microscope image of a small chip from a meteorite are several tiny structures that are possible microscopic fossils of primitive, bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. http://photojournal.jpl.nasa.gov/catalog/PIA00283

This photograph shows orange-colored carbonate mineral globules found in a meteorite, called ALH84001, believed to have once been a part of Mars. http://photojournal.jpl.nasa.gov/catalog/PIA00290

This electron microscope image is a close-up of the center part of photo number S96-12301. http://photojournal.jpl.nasa.gov/catalog/PIA00284

This high-resolution scanning electron microscope image shows an unusual tube-like structural form that is less than 1/100th the width of a human hair in size found in meteorite ALH84001, a meteorite believed to be of Martian origin. http://photojournal.jpl.nasa.gov/catalog/PIA00288