It's core would likely be iron-rich like a terrestrial planet, but that would be covered by layers of silicon carbide and titanium carbide, graphite, and possibly diamonds. The surface would feature a lot of hydrocarbons and carbon monoxide.
If water exists on the planet, it could lead to life. Since the ratios of silicon and carbon have been reversed, it's possible that the planet would evolve Silicon-based life. Since the ratios of oxygen and carbon in the atmosphere have been reverse, it's possible oxygen-compounds would be used as food and carbon would be respirated.
Stars in the Galactic Core have more carbon in them than stars near our own, so it's possible that carbon planets are the norm near the core.
Game and Story Use
- They'd be hell for humans to try to live on - and you can forget terraforming - but you could mine them. They'd be a source not only of diamond, but also of other carbon compounds we have yet to discover.
- With all that carbon, it's possible you'd end up with a planet that's just teeming with life.