  A new and mysterious class of object has been revealed by the detection of
numerous weak MgII doublets in quasar absorption line spectra. The properties
of these objects will be reviewed. They are not in close proximity to luminous
galaxies, yet they have metallicities close to the solar value; they are likely
to be self-enriched. A significant fraction of the weak MgII absorbers are
constrained to be less than 10 parsecs in size, yet they present a large
cross-section for absorption, indicating that there are more than a million
times more of them than there are luminous galaxies. They could be remnants of
Population III star clusters or tracers of supernova remnants in a population
of "failed dwarf galaxies" expected in cold dark matter structure formation
scenarios.
