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 (5 and 18 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 is tied with Silverstream for the smallest known non-trivial period 90 oscillator.
