  In bulk helimagnets, the presence of magnetic skyrmion lattices is always
accompanied by a periodic stress field due to the intrinsic magnetoelastic
coupling. The release of this nontrivial stress field at the surface causes a
periodic displacement field, which characterizes a novel particle-like property
of skyrmion: its surface configuration. Here, we derive the analytical solution
of this displacement field for semi-infinite cubic helimagnets when skyrmions
are present. For MnSi, we show that the skyrmion lattices have a bumpy surface
configuration characterized by periodically arranged peaks with a
characteristic height of about 10$^{-13}$ m. The pattern of the peaks can be
controlled by varying the strength of the applied magnetic field. Moreover, we
prove that the surface configuration varies together with the motion and
deformation of the skyrmion lattices. As a result, the surface configuration
can be tuned by application of electric current, mechanical loads, as well as
any other form of external field which has an effect on the skyrmions.
