Shh... Don't tell anyone but the "blueberries" are actually electrical concretions, not impact condensates... Just FYI. ;o]

See my notes on the blueberries posts. Especially the teslamania.com page on electrically shrunken coins and how they do it. There are actually several coins that shrunk electrically into hemispheres or spheres, or almost cylinders with a ring around the middle. Hmm, these look a lot like moqui marbles/shaman stones with hollow cores found on Earth in the southwest and elsewhere. I'm sure that if we started concertedly looking we'd find more...

Shh... Be vewwy vewwy quiet! I'm hunting electwical phenomena. Ehhehehehe... *wink*

If one wanted to make a really out there claim, they could ssay that spheres are evidence of electrical activity RATHER THAN impact activity, since we know that electricity can sculpt and eject material from surfaces in the lab, hence the lab process known as EDM (Electrical Discharge Machining). And EDM may also charicteristically leave spherical concretions of material scattered about on surfaces.

Amazingly, the Mars rovers are finding *drumroll* entire areas filled with blueberries as far the camera can see (okay, maybe slight exaggeration, but not by much)! Seriously, they're everywhere, and to be expected from an EDM standpoint toward "clean" cratering (IE scoops and gouges without a raised "crater" rim, smooth walls, no impact debris readily visible, but likely with tons of blueberries in surrounding areas; just an educated guess).