These are the original concept sketches for the Rock Lords. They were very obviously based on the "Devil Invaders" MRD-101 to MRD-105 (Casmodon, Falgos, Zarios, Gildis, Baldas). The first bears some resemblance to Granite, while the second is obviously similiar to Sticks 'n Stones. The fourth one strongly resembles the devil invader Casmodon. This some great concept art and shows how much work was originally put into the design of these toys.