  Hadron bubbles that nucleate with radius $R_{nuc}$ in a quark sea (if the
phase transition is first order) are shown to be unstable to the growth of
nonspherical structure when the bubble radii exceed a critical size of $20 -
10^3$ $R_{nuc}$. This instability is driven by a very thin layer of slowly
diffusing excess baryon number that forms on the surface of the bubble wall and
limits its growth. This instability occurs on a shorter length scale than those
studied previously and these effects can thus be important for both cosmology
and heavy ion collisions.
