Below is image of structural spheres, which Opportunity rover discovered 6.9.2012 (Sol 3064). Place is ancient river-bed, named Kirkwood in Endeavour crater. Broken objects have internal structure. Link to NASA news about these:
Puzzling Little Martian Spheres That Don't Taste Like 'Blueberries' .
Opportunity Sol 3247 contains also these same objects. Note that these spheres differ completely from small Blueberry spheres which exists widely on Mars surface.
Below are more details about Opportunity Sol 3064 and another discovery Sol 3247. Notice inside the spheres especially the two threaded extensions with small nodules at the other end (images A, B and C). In images C, D and J we see a clear shell layer and a center in these spheres. In spheres E and F we see a stem attaching these spheres to something. So these spheres have quite complex structure. Can these fine internal details, which are repeated again in another location, be result of random processes of nature ? Or are we actually looking at ancient fossilized life? These Spheres have been named Newberries and You can read more about them in Opportunity science team publication:
If we conclude that the Newberries are ancient fossilized life, then, as the result of evolution process, there are consequences for past and current life in Mars. If life was born in Mars, it must have been first primitive microbial life. Microbes survive even in extreme conditions of empty space [54]. And if there were microbes in early history of Mars then there are microbes even today, since a planet like Mars has always had good conditions for microbes, for example chemolithoautotrophs , in certain depth in underground soil. And the current conditions in soil at equator of Mars are good for certain type of microbes [12, 18]. There is moisture and water from 2 to 6 percent mixed in soil [41] and during daytime the soil temperature can be several hours even +36 degrees Celsius [63]. And there is all needed elements for life [17]. So if we think that Newberries are fossilized ancient life on Mars, then it is most probable that there is microbial life on Mars even today.
If we think that the Newberries are ancient fossilized life, then it is obvious that they are multicellular life and result of a longer evolution chain. Also it means that we could expect to find other species in images of Mars rovers. As you go further in this article, you will find out that this is the case.
It is notable that NASA scientists mandate the search of these kind of possible fossil structures in article published in July 2014:
D.J. Des Marais,NASA Ames Research Center 2014: Concepts Of Life In The Contexts Of Mars. .
Direct quote: "..Seek evidence of possibly biogenic physical structures, from microscopic (micronscale) to macroscopic (meter-scale), combining morphological, mineralogical, and chemical information where possible."
Biogenic structure is a structure produced by life process.
Another interesting article is in Astrobiology Magazine December 8 2014 by
Elizabeth Howell: How Did Life Become Complex, And Could It Happen Beyond Earth?
In this article Frank Rosenzweig, an evolutionary geneticist at the University of Montana, does not rule out development of multicellular life on Mars, Jupiter’s moon Europa and Saturn’s moon Titan.
Below left: Curiosity Sol-132 (19.12.2012). There is shiny object in stone, looking like a clam shell, named Mars flower. Candidate for past life? On middle(Sol-173) and right(Sol-186): White objects grow in size during 13 days. Candidate for current life on Mars?
In ancient sea floor in Antoniadi crater there is interesting formations, looking like coral-reef.
Below Opportunity Sol3247, microscopic imager camera image 1M416442430EFFBXSIP2956M2M1
Oppy Sol3247, image 1M416437725EFFBXSIP2956M2M4
Oppy Sol 3062
Oppy Sol 3067