Hi, BR and excellent work, Robert! Very sharp and no seams!!!

I'm going to keep my guess that this small crater Opportunity is in could very well be or related to what was once an active hot mud pot or even geyser. I'm still apprehensive about saying that (yes, Robert, I was kiddying below... although, you never know with Mars :}.

This one looks like a much smaller version than the one in Iceland (above):

An even smaller and even drier mud pot, but a good look at the texture of the 'mud' :

My first guess was that it was a Maar, but of course, the crater is much too small.

There's a frozen, frothyness to the texture of the layers, however they said at today's news conference that the top layers were surprisingly hard. I read that at the pots in Yellowstone, once the layers cool, they can be as hard as porcelain. The spherules could have been formed by ash and steam and were trapped in the 'soft' bedrock layers (Steve Squyres said this recently). We should be getting results on the spherules/blueberries soon. Then there's the high sulfer content.

Of course, I could be wrong.