Elkies' p5 is a period 5 oscillator that was found by Noam Elkies in 1997.
Elkies' p5 first occurred naturally in a soup found by Adam P. Goucher's apgsearch program in April 2015. Other efforts from apgsearch allowed a 15-glider synthesis of an 18-cell still life which can be converted to Elkies' p5. This 20-glider synthesis was completed by Brett Berger and Martin Grant. This was further improved to 8 gliders by Brett Berger and Martin Grant following a second natural occurrence in January 2016.