Spirit Sol 913 Sea Shells
More shells located in Gusev Crater
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More sea shells have been imaged by Spirit on Sol 913 at the wintering grounds where NASA has parked the rover.  The angled hillside provides best sunlight for the solar panels and allows the rover to continue operating well into its second year.  These new images show some excellent specimens that are without a doubt some of the clearest sea shells yet imaged on Mars.

The new book, "A Fossil Hunter's Guide to Mars" has the complete data on this and other findings.  You can buy it here.

This is a thumbnail of the L7 image from Spirit.  Click for a full sized version.  

This is from file 2P207413625EFFAS00P2278L7M1.  The original image is here at the NASA/JPL web site.
This is the thumbnail of the R1 image that I used to create the stereo images from.  Click the image for the full sized version.

The image data is from file 2P207413625EFFAS00P2278R1M1.  The original image is here at the NASA/JPL web site.

I have cropped out the sea shells and combined them in individual, stereo views.  The first is a broken open spiral shell and presents its spiral end directly to us.  You can see that it is perfectly round, wafer thin, and does indeed spiral at the tip.

Spiral sea shell from Spirit, Sol 913, located at the hillside where Spirit is wintering.

This second one is another species but identical to many terrestrial sea shells.  It is on its side and broken open.

A second sea shell in the same image frame.  This is very clear; no other item has this look or structure.

Now compare these side by side.  The center image is a terrestrial whelk shell found on a beach.  The far right image is the Spirit Sol 913 shell shown in the stereo image above.

The similarity is unmistakable.  This is clearly another Martian sea shell.

 
A third shell exists in the same frame and I have assembled a stereo view of it here.

This is to the far left of the "end-on" spiral shell, exactly opposite of the whelk shell.
This is a false color view of the spiral shell seen end on.  There are many intriguing objects in this frame, and many appear to be shells or coral.

All the source files for these images are on the NASA/JPL web site here.