Gmantoo, there is something linear there and the angles make it look artificial. I agree that it does not look like blueberries but it does look like a spray tampering application.
We have found many 'pipes' in other images so this may be the same but with the tampering it is hard to tell for sure.
I think this is more than just the small marble or bead-like things you see all over the place. This looks as it they are like the groung cover you see on some sand dunes at the beach (at least in the UK anyway). Maybe like seaholly or something plant-like very close to the ground. A couple of inches high. I suspect it is a crop.
Hi qmantoo, the blue stuff you see all over the place are the so called blueberries. These apparently could only be seen in Opportunity imagery, present in almost every image from the rover.
You can see where they go, and you can see that a lot of this blue stuff is tampering used to hide things. I have marked the pipes with yellow lines. See if you agree with me. The original here. a Maybe it is some kind of crop they are cultivating and need to pipe water to it to keep it going?