  Recent X-ray surveys have clearly demonstrated that a population of optically
dull, X-ray bright galaxies is emerging at X-ray fluxes of the order of 10-14
erg cm-2 s-1. The nature of these objects is still unknown. We present the
results of multiwavelength observations of what can be considered the best
studied example: the Chandra source CXOUJ031238.9-765134 optically identified
by Fiore et al. (2000) with an apparently normal galaxy at z=0.159 and called
``Fiore P3''.
