  Physical systems characterized by a shallow two-body bound or virtual state
are governed at large distances by a continuous-scale invariance, which is
broken to a discrete one when three or more particles come into play. This
symmetry induces a universal behavior for different systems, independent of the
details of the underlying interaction, rooted in the smallness of the ratio
$\ell/a_B \ll 1$, where the length $a_B$ is associated to the binding energy of
the two-body system $E_2=\hbar^2/m a_B^2$ and $\ell$ is the natural length
given by the interaction range. Efimov physics refers to this universal
behavior, which is often hidden by the on-set of system-specific non-universal
effects. In this work we identify universal properties by providing an explicit
link of physical systems to their unitary limit, in which
$a_B\rightarrow\infty$, and show that nuclear systems belong to this class of
universality.
