Yes, it's a rock. Looking closely at a rock, you'll see it's not gray, it's about a million colors. Amazingly deceiving. This was another adventure with my water-soluble crayons, those wonderful little marvels. I sketched this on wet paper, then rendered the colors as if they were colored pencil. Then once the colors were in place, went back in with the water and a brush, and moved color around here and there, adding the background and so on. LOVE the result. What do you think?