Mold was found by Achim Flammenkamp in 1988, but not widely known until Dean Hickerson rediscovered it (and named it) in August 1989. Compare with jam. In terms of its minimum population of 12 it ties with mazing as the smallest period 4 oscillator. But in terms of its 6×6 bounding box it wins outright. In fact, of all oscillators that fit in a 6×7 box it is the only one with period greater than 2. It is also the twelfth most common naturally-occurring oscillator, being less common than the spark coil but more common than the quadpole on ship.