Answer:
Marking mortal privation when firmly in place. An enduring summation inscribed in my face.
Alone I am 24th with a friend I am 20. Another friend and I am unclean.
I dance on one feet and knows only one shape. Someone with same name as me is very good with directions
I think you live beneath a roof that is upheld by me; I think you seldom walk abroad but my fair form you see; I close you in on every side you very dwelling pave and probably I'll go with you At last into the grave.
I can be in your body but never on your placemat. I'm always better when I'm fresh, but you'll never see me in the flesh. What am I?
Give it food and it will live, give it water and it will die.