I spent a lot of time playing around with mograph cloner in Cinema 4D to achieve the multitude of skulls randomly stacked in perspective. It shut down my processor and kept running out of memory. I needed to cut back on some of the skulls in C4D and multi composite in Photoshop. Just another road to rome but it took me to the same place. Many thanks to the great textures from the "CG Textures" website.