  The intrinsic shape of galactic bulges in nearby galaxies provides crucial
information to separate bulge types. We intended to derive accurate constraints
to the intrinsic shape of bulges to provide new clues on their formation
mechanisms and set new limitations for future simulations. We retrieved the
intrinsic shape of a sample of CALIFA bulges using a statistical approach.
Taking advantage of GalMer numerical simulations of binary mergers we estimated
the reliability of the procedure. Analyzing the $i$-band mock images of
resulting lenticular remnants, we studied the intrinsic shape of their bulges
at different galaxy inclinations. Finally, we introduced a new ($B/A$, $C/A$)
diagram to analyze possible correlations between the intrinsic shape and the
properties of bulges. We tested the method on simulated lenticular remnants,
finding that for galaxies with inclinations $25^{\circ} < \theta < 65^{\circ}$
we can safely derive the intrinsic shape of their bulges. We found that our
CALIFA bulges tend to be nearly oblate systems (66%), with a smaller fraction
of prolate spheroids (19%) and triaxial ellipsoids (15%). The majority of
triaxial bulges are in barred galaxies (75%). Moreover, we found that bulges
with low S\'ersic indices or in galaxies with low bulge-to-total luminosity
ratios form a heterogeneous class of objects; additionally, also bulges in
late-type galaxies or in less massive galaxies have no preference in being
oblate, prolate, or triaxial. On the contrary, bulges with high S\'ersic index,
in early-type galaxies, or in more massive galaxies are mostly oblate systems.
We concluded that various evolutionary pathways may coexist in galaxies, with
merging events and dissipative collapse being the main mechanisms driving the
formation of the most massive oblate bulges and bar evolution reshaping the
less massive triaxial bulges.
