The Pyrastar is a 2x2x2 modification from the same family as the Pyramorphinx and Pyradiamond. It is produced and sold by Uwe Meffert.
It differs from the other modifications in that it is in the shape of a Stella Octangula (or stellated octahedron if you prefer). If you find the pyramorphinx confusing, you'll find this more so. The problem with this one is working out which piece goes where before you select the 2x2x2 algorithm you want to use.