Pi-R-Squared spaceship

The Pi-R-Squared spaceship is a fictituous spaceship due to Dave Greene, supposedly consisting of two pi grandparents and two R-pentominos, with a population of 20 in a 55×34 bounding box, moving at speed c/137.

It was claimed to have been "seen briefly in 1974 on a PDP-12 display by Tony Honcho Jarnow" (an anagram of "John Horton Conway"), arising from the ash of a random 128×80 soup, "just before an unfortunate power outage due to tripping on a power cable".

The idea is that the R-pentomino and the five-cell pi grandparent are each fairly common and therefore likely to pop up in general, regardless of what the pattern was like dozens or hundreds of generations earlier (as long as it had not already adopted a stable/repeating configuration). If one of the many initial patterns that could lead to this also had two R-pentominos and two pi grandparents (in the same configuration), then that would result in a spaceship. In December 2020, Tanner Jacobi found a near-miss spaceship that relies on a similar principle, where two blocks and two traffic light predecessors, aided by a line of gutter symmetry, happen to form from the same arrangement 61 generations earlier plus one dot spark on each side.