That "stuff" in the lower right corner of the second pic is I think what they're discussing here:
"It is bizarre," said Steve Squyres, principal investigator on the NASA team. "It's strangely cohesive. It's not like anything I've ever seen before. It's weird stuff."
http://www.usatoday.com/news/science...rs-rover_x.htm
Weird stuff indeed, I don't know what to make of it.