Polonium: graphic showing the radioactive metalloid with atoms arranged in a simple cubic (primitive cubic) way, with one atom at each corner of a cube. Polonium is the only element like this. This is not close packed and is a strange arrangement. You can find more about this unique packing at the AIP site.
Image is 500 pixels across, the originals are 4096 pixels across.
(above) polonium atoms arranged in a simple (primitive) cubic pattern