is a Kupier Belt Object
and the third largest "dwarf planet", it is also very bright, almost pure white, very heavy for a distant object which should be largely water ice (mean density of basalt), cigar shaped, spinning rapidly and accompanied by two Moons. This adds up to a puzzle, and the favoured explanation was that these unusal features were due to an impact smashing off most of EB61's mantle.
Now Mike Brown
and his team have published in Nature a report on finding 5 smaller objects
in much the same orbit, which is consistent with the impact hypothesis. You can read further comment on this discovery at New Scientist