Blocker is a period 8 oscillator found by Robert Wainwright. It is a useful dot sparker consisting of two blocks hassling an unnamed object. It reappears half way through its cycle rotated through 180 degrees.
Blocker is about the sixteenth most common naturally-occurring oscillator in Achim Flammenkamp's census, being less common than mazing but more common than jam.
- ↑ Achim Flammenkamp (September 7, 2004). "Most seen natural occurring ash objects in Game of Life". Retrieved on January 15, 2009.