re:Mud? That wet stuff on my shoes?
Well Bob if you had read what Gary wrote and looked at the image you might have talked fossils. In the middle of the picture and a bit to the top is a couple of shapes that look a little like bivalves to me...
I have never said mud couldn't exist on Mars. We don't know the exact composition of the regolith at Gusev. If what we see is mud people will get. It if not it is still interesting as it will effect human operations on the planet.