The Skewb, invented by Tony Durham is a corner-turning twisty puzzle, consisting of 8 corner and 6 square center pieces. This puzzle is a Pyraminx shape-mod, working on the same 4 axes mechanism and this is why it was first called the Pyraminx Cube. If you take it apart you realize that it has the same inner cores and the four corners are actually centers and the other four pieces are edges.
Francis Cube Blog 