  We present first deep VLT-spectra of a new class of compact extraplanar
objects located in the disk-halo interface of the edge-on spiral galaxy NGC55.
Their spectra reveal continuum emission from stars and show typical
emission-lines as observed in ordinary disk HII-regions. Similar to the Diffuse
Ionized Gas (DIG) the prominent ionization stage of oxygen is O+, whereas the
corresponding one for low metallicity HII-regions is O++. A comparison with
CLOUDY model simulations reveals that the ionization mechanism of these compact
objects is most likely photoionization by late OB stars (O9.5 to B0). Further
analysis of diagnostic diagrams unambiguously confirms the HII-region
character. This raises the question whether these extraplanar HII-regions
(EHRs) originated from the prominent extraplanar gas of this galaxy or have
just been expelled from the disk into the halo. From hydrodynamical
considerations ejection from the disk can be ruled out. Therefore, these
objects must have formed within the halo. Compared to the average abundance of
the central disk HII-region (45% Z_solar) both EHRs reveal substantially lower
[O/H] abundances of about 10% Z_solar. We could establish for the first time
strong differences in the metal content along the minor axis of this galaxy.
Oxygen appears to be less abundant in the halo by about a factor of 4. Since
both EHRs are located above the central part of NGC55, it appears likely, that
their formation was triggered by star formation activity in the disk below. In
this environment the molecular gas clouds out of which EHRs have formed can
survive and collapse only in the period between two successive bursts of star
formation.
