A finite pattern is total aperiodic if it evolves in such a way that no cell in the plane is eventually periodic. The first example was found by Bill Gosper on November 16, 1997. A few days later, on November 19, he found the much smaller example that consists of three copies of backrake 2 (by David Buckingham), shown to the right.
On June 24, 2004, Gosper found that a block can be added to the pattern to make the total periodic pattern shown below, in which every cell eventually becomes periodic (albeit incredibly slowly). The block remains untouched for about 363 generations. It deletes its nth glider (and is shifted) at about generation 357.5+5.5n.