But that doesn't mean we can't look for seas shells in a previously flooded basin. There's lots to see, and finding pretty pebbles is a noble goal. Unusual shapes catch the eye, and beg for a close look. Would we even recognize a Martian fossil? What would it take to be convinced?
"I do not know what I may appear to the world, but to myself I seem to have been only a boy playing on the sea shore, and diverting myself now and then finding a smoother pebble or a prettier sea shell than ordinary whilst the great ocean of truth lay all undiscovered before me." Isaac Newton
|Is unlikely a sea shell. Detail of top-right of image below.|
At this location, at the Kimberly, there are lots of shiny pebbles embedded in a sandstone matrix. These are also not a dime-a-dozen on Mars -- it's not obvious how small stones get rounded and polished. Wave action and river transport is usually how it happens on earth.
The side of this sandstone block shows layering with roughly uniform thickness. On earth this would indicate seasonal deposition, perhaps due to annual fluctuations in composition.
Nearby some course grains with angular facets slowed erosion along an edge of a bedding plane.
Beneath the block sand slips down-slope.
Curiosity's robotic arm and instrument packages are even shinier, smoother and less likely.
"All computers are just carefully organized sand." xkcd.com/1349/This is the position at which the MARDI camera took the top images:
Just before moving to this position, a mast camera took this shot of one face of the arm's instrument package, to check that every thing was in order. Can't get much more ordered.
All Curiosity images that make it back to earth are available at: