Answer:
What goes in the water black and comes out red?
Taken from a mine and then locked up in a wooden case. I am used by students everyday.
I am full of holes but still holds water.
As I went over London Bridge I met my sister Jenny; I broke her neck and drank her blood and left her standing empty.
I am rubber you can eat!
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.