Spirit Find A Perfect Crinoid Fossil

Sol 343 images show a clear ancient organism on a rock face

   As Spirit climbs to higher ground, the layers of rock and sand thin out and expose the lowest strata.  These strata are nearly identical to those in Meridiani Planum, where Opportunity is finding so many geysers and fossils.  Gusev has its share of stromatolites and other organisms, but this crinoid is one of the best yet found.

   Modern crinoids are often called "sea lilies" because they strongly resemble plants or flowers.  In fact, crinoids are very ancient and go back about half a billion years on Earth.  They are more closely related to sea urchins and starfish, and are technically echinoderms (meaning rough skin).  They have a skeleton made of calcium carbonate, the same material that limestone and calcite are made of.

The find starts with these images from Spirit on Sol 343.  Many of these rocks have surface features that resemble coral, but nothing really clear enough to be certain.    This small rock to the lower left shows a curious imprint that appears to stand out slightly. The original image is here at the NASA/JPL site.
Here is the same rock magnified and presented in violet light, which has a higher resolution (sharper details).    Notice what appears to be a rounded feature to the lower left of the rock, and linear features stretching to the upper right?    Let's look at a contrast sharpened view and try to identify the features more clearly. The original image data is here at the NASA/JPL site.
This is a nearly perfect image and the markup shows the features that are present more clearly.    The rounded bulb is the "head" of the creature, or the calyx.  Its arms are used to filter feed by straining small organisms from the sea water.    The arms are very clear also.  Can we confirm that these features are real and not just some trick of light and shadow?  Yes.
By inverting the image (like a negative) and performing a high frequency spatial filtering, this image was was produced.  This image has been scaled up by 60%.    There is no doubt that the features are indeed identical to those of a crinoid.  Can we eliminate the possibility of this being some sort of artifact?  Yes.    Because all 13 images taken by NASA show the same features, in all wavelengths from deep infrared to violet light, and in two cameras, we can eliminate the possibility that either camera is causing a problem or that any filter is the cause.    And, since the released images are JPG, some people will think that this is an artifact of image compression.  But the images are made at varying resolutions due to the different wavelengths of light.    This proves that this is not an image artifact.

    Now, by assembling the image in color and stereo, we can see that the features persist in three dimensions.  This is not possible if this is simply an imaging artifact or an image compression artifact.  Therefore, this is an actual solid object and it is consistent in all spectra and through both cameras, and in three dimensions.  There is absolutely no way that this is an artifact- it is a real, solid fossil image.

What this image shows is the fossil remains of a crinoid head (known as the calyx) and its branches or arms.

This cross-eyed stereo view shows the calyx and branches of a crinoid fossil.  To people unfamiliar with the crinoid, it looks something like an octopus with its tentacles spread to the upper right.

    Now, let's compare this to a terrestrial crinoid fossil found right here on Earth.

Terrestrial crinoid fossil		Martian crinoid fossil

    This is clearly another example of a Martian fossil.  Combine this with the trilobites, stromatolites, sea urchins, sand dollars, squid, and other finds, and it is very clear that Mars was a planet covered with oceans that had ancient aquatic life almost identical to that found on Earth nearly half a billion years ago.