The term primordial black hole refers to the first black holes formed in the early universe, presumably resulting from different formation processes than those still occurring, such as the collapse of stars. Theories suggest the density variations left by inflation (a notion consistent with observed CMB anisotropies) might include sufficiently high densities to form black holes, i.e., above a Schwarzschild density. Theories also suggest they could result from topological defects. Theories vary regarding their resulting mass distribution, but generally suggest black holes smaller than stellar-mass black holes, with masses down to the minimum for a black hole and up into the mass range of asteroids. It is presumed that the small ones might have decayed, but the rest still exist. Because of their small size, the terms miniature black hole and micro black hole are sometimes used for some of them.