It looks like
Fordite.
Fordite "rocks" are created over time in industrial paint booths where they build up layers of paint on platforms, skids etc. The paint gets baked hard and is easily mistaken for a rock. Sometimes these are polished and mounted in jewelry. More frequently they are tumbled to smooth the edges and reveal the pattern.
Or it could be an orc egg. I see you included a gray background for scale. It looks about 1/4 inch or maybe 18 foot across? Is it hard? does it smell funny? Will it burn? Does it float? Did you find it in a cave on a mountain or your backyard? Does your dog bark at it? A little more information would help. Until then I'm sticking with Fordite.