We lost Mathematician John Conway to COVID-19 over the weekend. To us non mathematicians Conway was most well known for his Game of Life - a particularly interesting cellular automaton. If you poke around the web you can find all sorts of neat things relating to the Game of Life including a Turing Machine. Some times, I'd have classes explore the Game of Life and variants as a whole unit though more often, I use it as a stepping stone to using Cellular Automata to solve problems.