  Motivated by the LHCb's recent confirmation of $Z_1(4475)$ as the $J^P=1^+$
resonance, we investigate various exotic interpretations of $Z_1(4475)$, which
may be an axial vector tetraquark state, the P-wave excitation of the S-wave
$D_1 {\bar D}^\ast$ or $D_2 {\bar D}^\ast$ molecule, the S-wave molecule
composed of a $D$ or $D^*$ meson and a D-wave vector $D$ meson, or the cousin
molecular state of $Z_c(3900)$ and $Z_c(4020)$ composed of a $D$ or $D^*$ meson
and their radial excitations. With the help of the heavy quark symmetry, we
predict the typical radiative and hidden-charm and open-charm strong decay
patterns of $Z_1(4475)$, which are crucial to further identify the molecular
state assignment of $Z_1(4475)$.
