P18 bi-block hassler (or 43P18) is a period-18 oscillator discovered by Noam Elkies on February 20, 1995. In terms of its 43 cells, it is the smallest known period 18 oscillator. The unix on the bottom can be positioned in 2 places.
It is composed of two copies of unix that are hassling a bi-block, as shown below.
14 reveals that the oscillator is made up of two copies of unix and a bi-block.
- 43P18.1 at Heinrich Koenig's Game of Life Object Catalogs