Asteroid
Although their location in the asteroid belt excludes them from planet status, the three largest objects, Ceres, Vesta, and Pallas, are intact protoplanets that share many characteristics common to planets, and are atypical compared to the majority of "potato"-shaped asteroids. The fourth largest asteroid, Hygiea, has an undifferentiated interior, like the majority of asteroids. Between them, the four largest asteroids constitute half the mass of the asteroid belt.
Eunomia family
By far the largest member is 15 Eunomia, the largest of all the "stony" S-type asteroid, It is about 300 km across along its longest axis, has a 250 km mean radius, and lies close to the barycenter of the family. Eunomia has been estimated to contain about 70–75% of the matter from the original parent body. This had a mean diameter of about 280 km and was disrupted by the catastrophic impact that created the family. It is likely that the parent body was at least partly differentiated, because the surface of Eunomia and spectra of the smaller family members show some variation. This notwithstanding, other studies have indicated that the body that was definitively shattered by the impact that created the family was probably already somewhat fragmented by previous smaller collisions. The impactor was probably a smaller, yet still very substantial asteroid of 50 km diameter (or so) that hit at a speed of about 22,000 km/h.