That is probably how asteroids form. Little rocks and dust drift together from their gravitational pull, drawing more rocks and dust from their combined pull, eventually accumulating enough mass to form a lumpy pile of rocks and dust, and after a few million years they are stuck together as an asteroid. If they accumulate enough mass (the result of millions of years of collisions) their gravitational pull is sufficient to make them round planetoids, moons and planets.
and like a snowball rolling downhill, prolly has accumulated more mass than it started with...