Metal that's lighter than foam !

While looking up weights for Styrofoam, I got sidetracked by this article.
To paraphrase it:
Likely even more expensive and rare than the most precious unobtainium, it's pretty impressive what nanotechnology can come up with.
To paraphrase it:
Researchers have developed what they are billing as the world’s lightest material. With a density of 0.9 mg/cc, it is about one hundred times lighter than Styrofoam™


Likely even more expensive and rare than the most precious unobtainium, it's pretty impressive what nanotechnology can come up with.