In the Game of Life, a single live cell with no neighbours will become a dead cell in the next step. Therefore, any possible present state that has at least one past state has an infinite number of one-step-back states (which differ from the one state merely in having one or more neighbourless cells at random locations, far enough from anything else to have no effect).

Some of these one-step-back states may end up having evolved from simpler starting tilesets than the one with no vanishing cells.