84P87 is the smallest known period-87oscillator, discovered by Tanner Jacobi on January 27, 2016,[1] who used two copies of it to reduce the period-87 glider gun (that had previously been comprised of Herschel loops) no later than 2016-02-01.[2]Chris Cain reduced its bounding box further on 2016-04-06[3] by use of a p3 replacement for the eater to replace the eaters in the form shown by the infobox (that allow a 136-cell 41 × 39 variant of the oscillator itself), and since then, a period-3 catalyst was found that allowed a monomerisation using a single instance of 84P87, forming the former smallest period-87 glider gun.[4] On April 10, 2025, Aleph realized that a smaller catalyst could work, reducing the bounding box by three columns.[5]
