What would be interesting, why is his skin made of stone?
I’m thinking he was born with a genetic mutation that got worse over time, resulting in how he looks now. His skin mutated and turned grey, becoming harder and thicker, eventually turning into something that looks and acts like solid stone, but still sort of works as skin (nerves, blood vessels, etc.)
I hope that’s a good explanation. I’m still working on how/why a lot of these characters have their ‘powers’. 😀