  Here we highlight our recent results from the IFS study of Mrk178, the
closest metal-poor WR galaxy, and of IZw18, the most metal-poor star-forming
galaxy known in the local Universe. The IFS data of Mrk178 show the importance
of aperture effects on the search for WR features, and the extent to which
physical variations in the ISM properties can be detected. Our IFS data of
IZw18 reveal its entire nebular HeII4686-emitting region, and indicate for the
first time that peculiar, very hot (nearly) metal-free ionizing stars (called
here PopIII-star siblings) might hold the key to the HeII-ionization in IZw18.
