  We consider small-scale spheroidal clusters of weakly interacting massive
particles in our Galaxy as non-compact gravitational microlenses and predict
the appearance of caustics in the plane of a lensed source. The crossing of
these caustics by a lensed star can produce a large variety of light curves,
including some observed in actual microlensing events that have been
interpreted as manifestations of binary gravitational lenses. We consider also
observable effects during the gravitational microlensing of stars of non-zero
angular size with a given brightness distribution across their disks by such an
exotic objects as natural wormholes and objects whose space-time environment is
described with the NUT metric. We demonstrate that, under certain conditions,
the microlensing light curves, chromatic and polarizational effects due to the
properties of the lens and the star disk brightness distributions can differ
considerably from those observed for a Schwarzschild gravitational lens, so
that their analysis can facilitate the identification of such objects.
