  Recent experiments have led to active colloidal molecules which aggregate
from non-motile building blocks and acquire self-propulsion through their
non-reciprocal interactions. Here, we model the collective behavior of such
active molecules and predict, besides dynamic clusters, the existence of a
so-far unknown state of active matter made of 'active fractalytes' which are
motile crystallites featuring internal holes, gaps and a fractal dimension.
These structures could serve as a starting point for the creation of active
materials with a low density and mechanical properties that can be designed
through their fractal internal structure.
