This is a period-3 oscillator resulting from a collision between the 119P4H1V0 spaceship and a barrier of three vertical 2×2 blocks. It has a stable 13×13 bounding box.
Bounding box: 13×13
Population: 48
Period: 3
x = 13, y = 13, rule = B3/S23
2b3o3b3o2b$
13b$
1o4b1o1b1o4b1o$
1o4b1o1b1o4b1o ...