|View static image|
|Number of cells||38|
|Discovered by||Mitchell Riley|
|Year of discovery||2006|
Riley's breeder is a suprisingly small 38-cell quadratic growth pattern, discovered by Mitchell Riley in July 2006. It comprises a puffer train and two LWSSes. It produces a switch engine every 140 generations, filling three eighths of the Life plane. It has fewer cells than metacatacryst, and fits in a bounding box several orders of magnitude smaller.
It was originally discovered as a 40-cell pattern, but can be backtracked two generations by replacing the B-heptomino with a hexaplet.