I see it now or saw it early this morning on my phone ... at work now, will try to pull it up here in a bit. Is there information on what animals might look like on Mars, i.e. taking into account gravity, atmosphere, etc? Would be sophisticated guesswork I guess - but that might help evaluate.
Dimitar Sasselov, the Harvard astrophist whose presentation I cited several months ago from the 2007 Edge summer symposium "Life: What a Concept," offers insights into how life arises from a long chain of interactions in complex chemistry and goes on to speculate about evolutionary convergence possible on planets similar to ours. Here's the link to his written presentation (also available on video):
Dimitar D. Sasselov | Edge.org
I recommend reading the whole of it for the avenue it opens to our contemplating panspermia in general and specifically the likelihood of evolutionary convergence in life on planets similar to our own. Mars is generally recognized as likely to have been similar to our planet in its chemical and biological make-up and thus in the evolution of life there, but at periods of time earlier than our planet's known evolution of life.
The visual images returned from several sites on Mars by the rovers the US has sent there (primarily Spirit, Opportunity, and Curiosity) provide evidence of former life forms similar to Earth's in the often eroded sculptural representations of both human and animal species on the Mars surface, and as well in the buildings still visible on the surface amid the ruins of others structures. Scientists have reasoned that at some time in the past, after one or more environmentally damaging events, intelligent races on Mars, if they evolved*, have relocated for the most part to lava tubes beneath the surface. Images returned from Opportunity and especially Curiosity provide visual evidence of a variety of humanoid species still living on Mars and photographed during mid-day, when the Sun's light is strongest and the temperatures are considerably warmer than they are during the nights. It has been speculated by Mars researchers outside of NASA/JPL that the many humanoid beings and some 'lower' beings visible in those images might 'take the sun' at midday in order to absorb Vitamin D, and also to visit the scenes of past cultures and civilizations on Mars, for human types are often captured doing just that in groups and even families with children. It's also clear in some of these images that some intelligent and creative members of extant human-like species continue to produce artworks -- especially sculptures -- in areas near their entrances to the Martian underground. In such areas, entrances leading into hillsides and also downward on flat terrain are unmistakable, sometimes decorated with artefacts that appear to be relics of earlier periods of time on Mars.
I've been studying these JPL-released images, both in raw form and as enhanced with light, contrast, and other adjustments available in ordinary photo editing software, and in improved versions of those technologies, for about a year now. It is an absorbing subject. I personally still only use the basic photo editing technology available to me in Windows Live Photo Gallery, but long-time researchers of these images, which I study every day, use the more advanced technologies and bring out deeper information available in the raw images.
My general impression at this point (actually a conviction by now) is that there are indeed living species of various kinds on Mars today and that these are strikingly similar to species we know on earth.
*re ongoing evolution on Mars, it does appear that human-looking species visible in the Mars images are probably all smaller than average humans, and that some are considerably smaller, the latter producing small dwelling-places for their time spent on the surface.
The possible arthropod I discovered in the image I posted was invisible in the light-enhanced raw image I was studying until the point at which I made some adjustments in color temperature, tint, and saturation, when the possible critter suddenly appeared and, as I mentioned, startled me. It might be the case that there is no critter there but only an optical illusion of a critter, that what is 'there' in the image is only the rough side of a broken rock. But to me this looks like a biological creature that, if it were on earth, would be classified among the various arthropods known so far on earth, which is why I want to share the photo with an entymologist specializing in such species on earth. The elements that persuade me that it might be such a creature include its spots [similar, as I said earlier, to several large snakes I've seen in a few Mars images, including one image that included a whole such snake and a short distance away one that had been cut up in pieces]. Its curious bodily characteristics [fleshy at what appears to be its forward end and segmented at the rear] combine characteristics that may or may not occur together in similar earth species (though it seems to me that the anatomy of such insects as dragonflies combine a solid thorax with a segmented abdomen/tail.
{from a page on dragonfly anatomy:
"Abdomen
The abdomen always has ten segments. Segments 1 and 2 appear to be integrated into the thorax and are sometimes difficult to tell from the thorax. To find a particular segment, it is usually best to start with segment 10, far out at the tip, and count backwards. Because of its segmented nature, the abdomen is very flexible and is able to arch up or down (but not side to side). Learn to count abdomen segments as many of our descriptions are based on them.The male abdomen is often narrower (“waisted”) at segment 3, whereas the female abdomen is almost always more robust."}
The possible critter in my photo also has suggestions of legs, a few of them stretched out and more visible thought others are barely visible.
Finally, I've seen insects and also small amphibians on earth that apparently seek safety by aligning themselves with other structures in the environment, often structures [leaves, twigs] that also provide camouflage. If my critter is like these, it might be clinging to the side of a rock that provides the protection of camouflage.
On the other hand, perhaps there's no critter there after all. There's no way to be sure until we send biologists to Mars, which would be okay with me as opposed to sending oil drillers, for example, or worse: terraformers seeking to provide a new colony for humans, who tend to take territory from one another without asking for permission from the natives.