In CA evolution, 1D cellular automaton is visualized as a single line, its evolution along time and down a page produces a 2D plane. If we view the evolution of layers of a 2D cellular automaton we get a 3D object. I think that if we view the evolution of a 3D cellular automaton along time we are actually viewing a 4D object, i.e. 3 space dimensions and 1 time dimension. This is how I choose to view this objects. Generally we can say that when visualizing a N dimensional Cellular Automaton in Time we are actually visualizing an N+1 dimensional object.