At the time of writing there are fourteen stars known to have an iron content below 3.16 e-5 that of the Sun. Twelve out of fourteen of these stars are extremely enhanced in carbon, so that their total metal content Z is larger than 1e-3 that of the Sun, although their iron content may be lower than 1.e-7 that of the Sun. I will summarize extant observations of these very iron poor stars. New radial velocity measurements, implying binarity in one of these stars, have revived the theoretical view that this extreme carbon enhancement is the result of mass transfer from a former AGB companion, in contrast with the more popular view, that it reflects the chemical composition of the gas cloud out of which the star was formed. I will also provide an outlook on how current and future surveys may provide us larger samples of these extremely rare objects.