  The simplistic model of the classical spacetime foam is considered, which
consists of static wormholes embedded in Minkowski spacetime. We explicitly
demonstrate that such a foam structure leads to a topological bias of
point-like sources which can equally be interpreted as the presence of a dark
halo around any point source. It is shown that a non-trivial halo appears on
scales where the topological structure possesses a local inhomogeneity, while
the homogeneous structure reduces to a constant renormalization of the
intensity of sources. We also show that in general dark halos possess both
(positive and negative) signs depending on scales and specific properties of
topological structure of space.
