Fumarole on p18 bi-block hassler is a period-90oscillator that is composed of a fumarole and p18 bi-block hassler. Although it is composed of two oscillators of smaller periods (p5 and p18 respectively), it is considered non-trivial because it contains a single cell that is alive in generation 83 and dead in the other 89 phases of the oscillator. In terms of its 61 cells, it was tied with "Silverstream"[1] for the smallest known non-trivial period 90 oscillator, before discovery of thumb 1 on queen bee shuttle with 56 cells.
