  Looking at the region connecting two clusters is a promising way to identify
and study the Warm-Hot Intergalactic Medium. Observations show that the
spectrum of the bridge between A3556 and A3558 has a stronger soft X-ray
emission than the nearby region. Suzaku observations could not discriminate the
origin of the extra emission. In this work we analyze a dedicated Chandra
observation of the same target to identify point sources and characterize the
background emission in the bridge. We find that the count number of the point
sources is much higher than average field population (using CDFS~4~Ms as a
reference). Moreover, the shape of the cumulative distribution resembles that
of galaxy distribution suggesting that the point sources are galaxies in a
filament. The Suzaku extra emission is well explained by the high abundance of
point sources identified by Chandra. Furthermore, we used optical/IR
observations of point sources in the same field to estimate the density of the
putative filament as rho~150 rho_b$, below Suzaku sensitivity.
