Annual Review of Physiology VOL 58, 2018

The review by Walsh points out that these so-called rubble piles are not bound by atomic forces, like rocks,
but are weakly bound by self-gravity and are by-products of the continual collisional evolution of the Main Asteroid Belt. The related review by Hughes et al. pursues the subject by considering debris disks around other stars. These are composed of second generation dust produced by the grinding collisions of planetesimals, i.e., the same stuff of which rubble-pile asteroids were made