Miscellaneous ideas topic.
knowing the HP magic system any sort of creature like that would be kinda screwed up in one way or another retarded sort of way, aging would just be a slow development do to lack of constant magical influence upon harry, sorta the idea that 'those red stones' as you put it are like super dense chunks of raw magic energy or something and without the total amount, having maybe gotten just 1 he has to absorb ambient magic energy from around him, there wouldn't be much in privet drive, which would account for his malnurished and underdeveloped apperance, now once he gets to hogwart.......
well lets just say that things get interesting, especially considering the amount of magic that has not only been absorbed by the castle itself but the shear amount let off by students each day, not counting each year......hey, might not be a 'red stone' but it sure as hell will do at least part of the job.