  Most meteorites are fragments from recent collisions experienced in the
asteroid belt. In such a hyper-velocity collision, the smaller collision
partner is destroyed, whereas a crater on the asteroid is formed or it is
entirely disrupted, too. The present size distribution of the asteroid belt
suggests that an asteroid with 100 km radius is encountered $10^{14}$ times
during the lifetime of the Solar System by objects larger than 10 cm in radius;
the formed craters cover the surface of the asteroid about 100 times. We
present a Monte Carlo code that takes into account the statistical bombardment
of individual infinitesimally small surface elements, the subsequent compaction
of the underlying material, the formation of a crater and a regolith layer. For
the entire asteroid, 10,000 individual surface elements are calculated. We
compare the ejected material from the calculated craters with the shock stage
of meteorites with low petrologic type and find that these most likely stem
from smaller parent bodies that do not possess a significant regolith layer.
For larger objects, which accrete a regolith layer, a prediction of the
thickness depending on the largest visible crater can be made. Additionally, we
compare the crater distribution of an object initially 100 km in radius with
the shape model of the asteroid (21) Lutetia, assuming it to be initially
formed spherical with a radius that is equal to its longest present ellipsoid
length. Here, we find the shapes of both objects to show resemblance to each
other.
