i have a piece of marble queen pothos with no leaf attached. i put it in water to see if it would grow any roots, and it appears have to grown something which is a little more firm than what i'm used to when it comes to roots. is it forming a new root? :)

Your best bet would be to remove it from water and just plant it in a small pot of soil. All that brown on there is the start of rot. You should treat it with a fungicide before you plant it.