The Moss is an Inventory Item that can be used in the game.
The Moss is a dripping wet green stringy hanging plant.
The Moss can be found hanging from the tap on the right side of the prison cell.
Josef can simply pick the Moss from the tap.
The Moss can be used to make Tobacco. If Josef places the Moss onto the electric light in the prison cell the heat from the light will dry the moss. The dried Moss can then be used as a substitute for Tobacco.