Never been to Mars, don't know what it could be :-). Also, by "any natural
process" you probably mean nature on our planet. We simply don't know enough
about "nature" on Mars to jump into any conclusions by just looking at some
shapes on photographs. Anyway, I havee seen similar "structures" on Earch,
too: just look under some rocks after rain. Also, if I look on the picture
you posted long enough, I start seeing impressions or faces with distinctly
recognizable eyes, nostrils and beaks. Do you think these are fossil
impressions? What about those little dark and light grains - bacteria? :-)

"Informer" wrote in message
ink.net...
After Opportunity used the RAT to shave through one of the rocks in the
outcrop it revealed at least two puzzling, fossil-like structures. See
attached enhancement. Can anyone explain what this might be? One looks
like the "positive" and the other the "negative" impression within the
folds
of the rock. I cannot think of any natural process that would created
stuctures like this. They truly look like fossils but I am not jumping to
any conclusions. Have a gander for yourself and post your thoughts.