  The heterogeneous coexistence of antiferromagnetism (SDW) and
superconductivity on a mesoscopic scale was observed in iron-pnictides in many
recent experiments. We suggest and discuss the scenario in which the
heterogeneity is caused by formation of domain walls inherent to the SDW state
of pnictides at a proper doping or under applied pressure. Superconductivity
would emerge from the modulated SDW structure. The phenomenon is akin to the
FFLO-phase in superconductors.
