Mars: Possibility of Life

Lifeless.....or is it?

   There is talk that Mars in its lifetime may have once harbored life on it, but evidence of this is very vast and scarce. It does have the three necessary elements that scientists have confirmed to be the way that life can thrive on a planet.
                                      1. Chemical elements such as carbon, hydrogen, oxygen, and nitrogen
                                      2. A source of energy that living organisms can use
                                      3. Liquid Water
The source of heat for the planet could come from the sun itself or from within it's core for animals that live beneath ground or between the cracks. Water beneath the surface could still be liquid from the core heat while it is ice that has about a 3 feet thickness, 1 meter, near the south pole and perhaps maybe near the north pole.