Autonomous device for attacking wild replicators such as nanoswarms.
In the aftermath of the Nanoswarms of the pre-First Federation period, many autonomous nano-immune systems were set up across civilised space. Some were mobile or themselves replicators, intended to scout for emerging swarms and attack them. Over time such autonomous defenses spread and new ones were designed, especially by the Caretaker Gods. On the frontier, polemovores were discovered from extinct civilisations, and expanding anti-swarming systems proliferated. They became known as regulons, the natural predators of wild replicators - and sometimes each other.
Some eschatologists have worried that the regulons will evolve into a threat. Just keeping them from attacking each other has proven nearly impossible, and there is a risk that they might turn on civilised space as being a particularly unusual form of nano-infestation. As long as the nanodefenses of civilisation are better than any regulons this may not be a problem, but if the regulons should ever evolve beyond the ability of being stopped then they might wipe out everything.
According to some thinkers such as Urkan da Nstedt this might be the explanation for the fall of most galactic cultures and the stories about the Dawn Hunters: in the long run all civilisations have to create regulons, but the regulons eventually turn on their civilisation. In the end only a few regulons remain, slowly dying out.