This stuff was done using 3DSMAX, Maya and ZBrush. They consist of polygon based wireframe meshes, 'NURB' spline cages or 'pixols' respectively. Typically, various bitmaps have been applied to simulate texture and fine surface detail - all common techniques. I have loads more examples than are shown here, but they are a bit low res and sadly appear crude by today's standards... produced in the earliest days of 3D games.