  We investigate experimentally and numerically the defect configurations
emerging when a cholesteric liquid crystal is confined to a spherical shell. We
uncover a rich scenario of defect configurations, some of them non-existent in
nematic shells, where new types of defects are stabilized by the helical
ordering of the liquid crystal. In contrast to nematic shells, here defects are
not simple singular points or lines, but have a large structured core.
Specifically, we observe five different types of cholesteric shells. We study
the statistical distribution of the different types of shells as a function of
the two relevant geometrical dimensionless parameters of the system. By playing
with these parameters, we are able to induce transitions between different
types of shells. These transitions involve interesting topological
transformations in which the defects recombine to form new structures.
Surprisingly, the defects do not approach each other by taking the shorter
distance route (geodesic), but by following intricate paths.
