There is no conclusive evidence that life ever existed on Mars. However, there are some photos taken by the Mars Global Surveyor (MGS) that point to life forms on Mars, and others that support evidence of intelligent life.
This photo points to sand dunes on Mars, and is located in the southern hemisphere of the Red Planet. It resembles aerial view of Earth's deserts covered by shrubs. A Hungarian research team, studying these photos on similar areas believes that the black dots are living trees or shrubs. The NASA research teams, however, disagree. Their findings suggest that the dark spots are the effects of defrosting process on Mars and are not signs of life.
This is another photo that is much like spread trees, when seen from above. The renowned author Arthur C. Clarke feels they are like Earth's Banyan trees. Many photos taken during different times of a year, show that these forms change with seasons, growing during the increased warmth of Mars's spring season, just like any vegetation. NASA has again rejected this theory, and explained these away as defrosting phenomenon.
There have been some images with structures that look more artificial than natural. One of such photos shows a fascinating tunnel like structure, resembling an uneven tube. The structure partially under surface terrain seems as though it has been unearthed by a geologic process. NASA's theory on these structures is that they are quiet natural and are only sand dune rows.
One needs to understand that these are only theories and NASA's stance is no better than Hungarian theory.
These are among the most mysterious structures to have been photographed on Mars's surface. They are like long translucent tubes supported by rows of arches. There have been many guesses on this object. Some feel these could be large water channels funneling water from one area to another. Others say these are one of geological anomalies of Mars.
This supposed 'port' is a structure on a Martian cliffside that resembles a two-story building constructed for a mysterious purpose. The first floor walls of the 'port' are facing camera and in shadow. The second floor is at 45-degree angle to the first floor. Located on the roof of the second floor is a sharp circle, similar to helipads on tall buildings. Beside this structure is a huge U-shaped drain, flowing a great deal of liquid.
The "Mars Tower" seems very much like a tall tower having a white tip, casting extensive shadow around. It is around 6 kilometers high, about 10 times higher than the largest skyscraper on Earth. Many have wondered whether these are just optical illusions or an artificial structure of a lost civilization on Mars.
In Cydonia area of Mars, there are many anomalous structures. Below this region is a group of structures that have been called "pyramids". They have smooth triangular sides strikingly resembling the Egyptian Pyramid.
Scientists have always refuted the presence of water on Mars. This photo taken by Mars Express Orbiter in a way challenges their theories. Resembling a blue green "something", these patches are very much like a water body. Are there actual riverbeds on Mars? Recently Scientists found "water everywhere" on the Red Planet. Or are they a kind of blue-green algae or lichen anomalous to Mars?
Sir Charles W. Shults III, in his "A Fossil Hunter's Guide to Mars", uncovered several photos of objects taken by the Spirit rover on the surface of Mars. They resemble terrestrial seashells. These cannot be rocks, and if they are, then they are indeed anomalous to Mars.
When astronomer David Martines was exploring Google Mars, he found a structure resembling a large building, in the northern hemisphere of the planet. He called it "Bio-Station Alpha". He feels there may be some kind of a creature living in it. The structure is over 700 feet long and 150 feet wide. It may be located at the following coordinates on Google Mars: 71 49'19.73"N 29 33'06.53"W
This Golf Ball Crater is one of the strangest craters on Mars. It is so called because in its centre is a dome like structure, nearly spherical, and appears to have a golf ball texture. Interestingly, this dome is close to what seems like a series of tunnels that run above and below the Martian surface. Small tunnels apparently connect large tunnels, very much like a large drainage system.
These strange formations have been dubbed "Star City". It is a complex structure that some that resembles artificial wall constructions. Star City is located on the Syrtis Major Planum area and is part of a larger area that is home to geometric objects and structures that look like tubes and tunnels. Were they part of a real Martian city? It is not sure and some scientists feel these are just natural formations.