[en] The equation is derived, similar to the Bohr-Mottelson one, which describes the rotation and vibrations of the nuclear ellipsoid of inertia. Using it we considered the dynamics of nonrotating nuclei, whose energy landscape has minima corresponding to prolate and oblate shapes, connected by the collective path, along which the triaxiality parameter γ varies from γ = 0 to π/3. Peculiarities of the barrier tunneling in γ direction are considered with the aid of the modified WKB approximation. The electric-monopole-transition strength between the levels of the ground 0⁺ doublet of the nuclei with mixed prolate-oblate shapes is calculated. The results are consistent with the experimental data for Kr isotopes.