  In growing neutrino models, the neutrino mass increases in time and stops the
dynamical evolution of a dark energy scalar field, thus explaining the 'why
now' problem. A new attractive force, mediated by the 'cosmon' scalar field,
makes non relativistic neutrino form lumps on the scales of superclusters and
beyond. Nonlinear neutrino lumps are predicted to form at redshift z ~ 1 and,
if observed, could be an indication for a new attractive force stronger than
gravity.
