buckey balls and blueberries
Yeah, the group working on the PT impact, Lu Ann Becker (Seattle) and Poreda (New York) originally released their PT impact marker from buckey balls, but they were formed in space, and not by impact, if I remember right -
what this team is looking at appears (to me at least) to be similar to the "blueberries" on Mars - the question is whether the blueberries' iron came from iron or stony-iron asteroid impact, or Mars suface...
hope that helps...
ed