re: Isn't the discovery of Neptune what put an end to Ceres planetary status?
Not sure about that one, Raoul, but if Ceres was ever considered to be a planet it may have been because of it's 'roundness', but because it resides in the asteroid belt and it does have company, i.e., Juno, Vesta, Pallas, et al., it is not a planet. MHO.
They may be 'very old remnants' of our early solar system and even remnants of that hypothesized planet that may have harbored between Mars and Jupiter. That huge universal jury is still out on that one.