["If we were encountering fossils, how would we know? How would we be certain that the "worms" aren't fossils?"]

The recognition of fossils can be difficult, it's true. While the ancients recognized the simple fossils, most of paleontological knowledge has been a modern discovery. Strangely enough, geology and paleonntology are both ancient and very modern disciplines.

It begins with comparison to modern creatures. The ones we can observe help to postulate the extinct ones, and it is an inexact science for many reasons.

Some thoughts on why these are not fossils:

Even fossilizing hard animal and plant parts is a rare process. Everything has got to go just right to get fossil bones, shells, etc. Soft part fossils are very, very rare. Volcanic ash is great for preserving fossils and soft parts. Check out The Florissant Fossil Beds, Colorado. Anoxic mud works great too (like the Burgess Shale). Some of these soft fossils can be no more than a film and very strange looking, pretty much impossible to describle the animal that made them. It took a long time for hard part animals to appear on earth. I seriously doubt that worms would be preserved like this.

But that brings up "trace fossils" like footprints, worm trails or burrows. The science of bioturbation can be complicated but a basic is that worms cannot burrow up into sediment that is not there yet. In other words, the burrow has a top entrance which will terminate at a bedding plane. It gets complicated when there is a pulse of sedimentation, then burrowing activity, then another pulse of sediment, then more burrowing down throught the previous layers. Makes for some weird patterns. Pretty neat, though, I've seen some exposures of trace fossils that'd blow your mind.

There's a problem with rock type. If this is an altered basalt (I know that's one of the big models now, but I'm not convinced) then no way on the worm thing. I doubt you could find a bioturbated basalt on the sample wall in Hawaii. If this is a sulfate dune deposit, I really have a hard time picturing a worm living in that enviroment. Even if wet. Much of the rock is composed of epsom salt, gypsum, and jarosite. Worms wouldn't care for this too much. Or most life forms. Furthermore, the aeolean enviroment is really poor at preserving fossils, hard or soft.

If this is a sulfate altered rock from some other sediment...well, I see no evidence of that yet. We need to see more of the stratigraphy!

["But there is more to it. The layering everywhere investigated so far is showing lines of little beads making up the edges of the layers. But when the matrix is ground, no layers show behind this surface. Is the layering primary, then, or is it an erosional phenomenon? If it is primary, why don't we see discreet layers in the RAT ground surfaces? If it is erosional, how does this erosion take place? Sandblasting doesn't make such exquisite beaded edges. Does it?"]

I believe sandblasting is doing a great job of exposing the primary textures and structures of the outcrop.
I believe the layering is primary. Sometimes, especially with soft rocks where the layering is all the same color, a weathered surface shows you more than a fresh surface does. The differential erosion of layers carves out the structures and textures of the rock. Also, if the fresh surface (RAT'd) were wet, we'd see those textures alot better. Everytime I smash a rock I spit on the fresh surface. Or I pour some water on it. It makes a huge difference in what you see. Not gonna happen here though, Rovers got no spit, just like dogs in the desert.

I think Nick's sabka environment makes alot of sense and fits alot of the data. Perhaps the blueberry jam (or raspberry, given the differnet composition) forms on the top of a former surface after it is wet and dries up, then more dune material is blown in during a dry period, then there is more mosture, etc...

About the chocolate bar, it was pretty warm day for skiing, March is great in the Rockies! The snow was packed powder, not really all that wet, really. Just enough water to disolve a little sugar from the chocolate and start the diffusion process.

Enjoy your day...