  Observations revealed rich dynamics within prominences, the cool 10,000 K,
macroscopic (sizes of order 100 Mm) "clouds" in the million degree solar
corona. Even quiescent prominences are continuously perturbed by hot, rising
bubbles. Since prominence matter is hundredfold denser than coronal plasma,
this bubbling is related to Rayleigh-Taylor instabilities. Here we report on
true macroscopic simulations well into this bubbling phase, adopting a
magnetohydrodynamic description from chromospheric layers up to 30 Mm height.
Our virtual prominences rapidly establish fully non-linear (magneto)convective
motions where hot bubbles interplay with falling pillars, with dynamical
details including upwelling pillars forming within bubbles. Our simulations
show impacting Rayleigh-Taylor fingers reflecting on transition region plasma,
ensuring that cool, dense chromospheric material gets mixed with prominence
matter up to very large heights. This offers an explanation for the return mass
cycle mystery for prominence material. Synthetic views at extreme ultraviolet
wavelengths show remarkable agreement with observations, with clear indications
of shear-flow induced fragmentations.
