I don't know what that segmented worm-looking thing was that the RAT dislodged/destroyed the other day, but it sure is evocative. If it is not a fossil (and I'm betting it's not) we need some explanation of how rock can form into such a remarkable set of curving segments. How and why.

On the other hand, Mars has an amazing ability to mimic things we recognize and respond to. This has a tendency to drive observers nuts because we really don't know at any given time whether what we think we're seeing and studying is what it appears to be (often it's not) nor do we know that it is NOT what it appears to be.

The more I look at the Opportunity outcrop, the less it seems like rock. The more it seems to be dissolving, getting eaten away.

If the outcrop represents typical light colored ("white") material in Meridiani, then there is a HUGE amount of it close to the surface and just below it. If this material is basically the same as the "White Rock" material found in many craters (and between them in some cases) then there is far more of it than we might have thought.

It indicates a remarkable water regime -- but not necessarily an oceanic regime.

Could these deposits have originated below the surface? Is it possible that they are still being created?

Are the deposits reacting with ultraviolet light? With the atmosphere? Chemically reacting to the soil?

If these deposits were made in a watery enviornment of some sort, one that could -- and let's say did -- support life, complex life, would there be fossils, and how would we recognize them? Fossils are rare on Earth, after all. And not everything that looks like a fossil is one. Sometimes actual fossils look nothing like the remains of a living organism.

How would we know what we are looking at on Mars?

Sweet mystery!

Cheers, BRFelix