I agree this is a great find, but something is out of place with the top of large rock, my guess is the rock has been added to hide the base of the tall object, the image holds lots of anomalies not obvious when first viewed.
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"Creating a fiction when stating a fact destroys the credibility of the truth one are trying to convey"
The tall object looks like a head statue although I could be wrong, but to me that is what it appears to be.
I have produced a colour-difference version of this image and the tall object is definitely a different colour than the colour of the large rock it sits on.
There are also many other objects worthy of note in the view.
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"All truth passes through three stages. First, it is ridiculed; Second, it is violently opposed; Third, it is accepted as being self-evident."
It is not often I find unusual activity in the curiosity ChemCam: Remote Micro-Images, but sol 642 set of four images holes appear that are not present in the first slide (far right), I do not think they are caused by the rovers laser and look more like they have been burrowed, I can't make out if there is anything else around the holes as I am using a mobile device to post this find, but I am sure members can dissect the image........ http://mars.jpl.nasa.gov/msl/multimedia/raw/?s=642&camera=CHEMCAM_
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"Creating a fiction when stating a fact destroys the credibility of the truth one are trying to convey"
I think it is shadow too, to me it looks like the end of a plinth or rectangle slab, there is one under the strange black object top right of the image also.
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"Creating a fiction when stating a fact destroys the credibility of the truth one are trying to convey"