Gases are produced which result in "a characteristic 'blow,' exchanging the material from deep underground for the matter on the surface above it."

At this stage, the spice of Arrakis forms a characteristic 'blow,' exchanging the material from deep underground for the matter on the surface above it.

When water is flooded into the sandtrout's excretions, a pre-spice mass is formed; at this "stage of fungusoid wild growth," gasses are produced which result in "a characteristic 'blow,' exchanging the material from deep underground for the matter on the surface above it."