As a general category of theories that's called "cold dark matter" — it needs to interact with something in order to clump up / cool off, but perhaps not in a w

As a general category of theories that's called "cold dark matter" — it needs to interact with something in order to clump up / cool off, but perhaps not in a way that's very visible to us. A wikipedia excursion will net you a handful of such theories and their pros and cons.