Why is this a Carbon World?Your planet's carbon (29.3%) outweighs its oxygen (22.6%), so the mineralogy flips from silicate rock to carbide - a graphite crust over a diamond mantle.
Carbon worlds form in carbon-rich disks where there isn't enough oxygen to bind it all into silicates. Instead carbon condenses directly into graphite, carbides, and - under pressure at depth - diamond. They form water-poor, so no life takes hold.
Inside the Roche limit (2.80 planet radii): torn apart into a ring system.
Moon 2receding1.8% - 22.0 radii
Outside the synchronous orbit: slowly receding, like Luna (~cm per year).
Tidal braking locked the planet to its moon: one face forever moonward.
+5 temperature: large moon stabilizes the axial tilt - steady seasons+4 chemistry: tidal pools cycle wet and dry - a boost for prebiotic chemistry+5 magneticField: a large close moon may help stir the core dynamo (speculative)