Thanks for the detailed answers :) I enjoyed reading these! I agree abut the prison planet being a fragment of a planet that was once whole, since nobody recognised it 'till they were up close.
I dig the theory about Jewelia being from rock -- but she looks too different to me, like a whole different species of person? With the prison planet being able to teleport, I imagine she could've come from another system...(So I guess that's my headcanon! My other theory is that Sternum was born a prince, to a king who basically only had children to protect a place on the throne.)