False-color image of the scanning electron micrograph of nanophase, amorphous iron prepared by the ultrasonic irradiation of iron pentacarbonyl solutions. The micrograph shows the porous, coral-like structure formed from nanometer-sized clusters created during acoustic cavitation. The amorphous iron is an extremely soft ferromagnetic material with high catalytic activity. Magnification of the cover image is approximately 100,000. The micrograph was obtained on a Hitachi S800 SEM in the UIUC Center for Microanalysis of Materials, which is supported by the US Department of Energy. Courtesy of Kenneth S. Suslick, Mark W. Grinstaff, and James A. Gray, School of Chemical Sciences, Univ. of Illinois at Urbana-Champaign.