Very gas-rich extremely metal-poor blue void dwarfs
  Half-dozen of extreme representatives of void dwarf galaxy population were
found in our study of evolutionary status of a hundred galaxies in the nearby
Lynx-Cancer void. They are very gas-rich, extremely low-metallicity [7.0 <
12+log(O/H)< ~7.3] objects, with blue colours of outer parts. The colours
indicate the ages of the oldest visible stellar population of one to a few Gyr.
They all are intrinsically faint, mostly Low Surface Brightness dwarfs, with
M_B range of -9.5 to -14 mag. Thus, their finding is a subject of the severe
observational selection. The recent advancement in search for such objects in
other nearby voids resulted in doubled their total number. We summarize all
available data on this group of unusual void dwarf galaxies and discuss them in
the general context of very low metallicity galaxies and their possible
formation and evolutionary scenarios.
