Below is a puncheon of Mourvèdre from Girard wildly fermenting. We don’t inoculate our wines with commercial yeast – instead we rely on the ancient method of just letting it ferment. Each vineyard seems to have its own specific yeast and each varietal has it own pattern.
In this case, the yeast is causing a very light, sea foam like, bubbling.
And yes, it is a pain to clean up.