The Day and Night cellular automaton
Although I could probably spend a few more years discussing the properties of life-like cellular automaton rules, I feel it is time to end the introductory series. I do so by giving an example of a shrinking black blob in the Day and Night automaton (B3678/S34678).
However, you need not panic: by putting the life-like cellular automata aside for now, I can spend time investigating other types of automata.