Spiral galaxies usually have 'bulges' at their centers. These bulges are huge, tightly packed groups of stars. However, using Galaxy Zoo volunteer classifications, it has been found that some spiral galaxies do not have bulges. Many galactic bulges are thought to host a supermassive black hole at their centers: however pure disk galaxies with no bulges but with growing central black holes were found. That pure disk galaxies and their central black holes may be consistent with a relation derived from elliptical and bulge-dominated galaxies with very different formation histories implies the details of stellar galaxy evolution and dynamics may not be fundamental to the co-evolution of galaxies and black holes. It seems that these bulgeless galaxies have formed in environments isolated from other galaxies. It is hypothesised that the black hole mass may be more tightly tied to the overall gravitational potential of a galaxy and therefore its dark matter halo, rather than to the dynamical bulge component.