  Cylindrical nanowires made of soft magnetic materials, in contrast to thin
strips, may host domain walls of two distinct topologies. Unexpectedly, we
evidence experimentally the dynamic transformation of topology upon wall motion
above a field threshold. Micromagnetic simulations highlight the underlying
precessional dynamics for one way of the transformation, involving the
nucleation of a Bloch-point singularity, however, fail to reproduce the reverse
process. This rare discrepancy between micromagnetic simulations and
experiments raises fascinating questions in material and computer science.
