Abstract: A natural problem in algebraic topology is Steenrod’s representability problem: Is every homology class of a space represented by the continuous image of the fundamental class of a closed manifold?. This question was solved by Rene Thom: Every homology class with Z/2Z-coefficients is represented, but there are homology classes with integer coefficients that are not represented. In this talk I will give a geometric description of homology classes with integer coefficients of BZ_p x BZ_p that are not representable and explain how the singularities look and why they cannot be removed. I will use stratifolds and Z/k-stratifolds to construct the classes and give a geometric description of the Atiyah-Hirzebruch Spectral Sequence of oriented bordism.