Present-day remnants of phase transitions in the early universe

At very early times in the universe history a number of phase transformations occurred which led to a large variety of relics such as: density and gravitational waves, topologically stable extended objects (monopolies, strings, domain walls, etc...), lumps of strange matter and, possibly, more. Most of these objects left imprints which may be discovered in today's universe looking at the complicated properties of the large-scale matter distribution