  In the transition from nuclear matter to finite nuclei, complex finite-size
effects which characterise open systems arise, in relation with either the
nuclear surface or the bulk. In addition, the non-equilibrium character of the
process, typical of violent heavy-ion collisions (from Fermi energy to the
intermediate-energy domain) adds up as well. The resulting dynamics is the
combination of surface and volume unstable modes which trigger large-amplitude
fluctuations. A rich variety of fragmentation patterns may emerge, ranging from
collimated streams of nuclear clusters to the split of a stretched nuclear
complex into few large fragments. They imply different conditions of density
and surface tension, and result in different chronologies. Such phenomenology
has been observed in experiments, but it is often difficult to recognise and
disentangle the underlying types of instabilities. To draw some example, two
extremely deformed nuclear systems, produced below and above Fermi energy, are
chosen and followed microscopically all along their evolution within the
Boltzmann-Langevin One-Body approach.
