Claywoman,<br /><br />You've made an impressive number of posts in a short time. If you'd been around earlier, you'd have seen more of these images, so it's okay that you have ignorance about it. Just wanted to set that out there, so you can tell that I'm not trying to be an ass.<br /><br />This is a microscopic imager picture from one of the Mars Rovers. If it were earlier in the eventing, I could tell you which one. We're looking at a 1"x1" (approximately) view of its own track. As it drives around, lots of small rocks get churned up. We've seen examples in every image that the science team takes.<br /><br />So it's just a small, flat rock.<br /><br />The ridges are probably real, and probably do tell a geologist something about how this rock formed: as it grew, or as something built up layers, or as something slowly squished it before it got carried to this spot.