For the Convergence, there is no single mind. As long as a Hive is alive, it can give commands or produce a new Praefectus. And with a Praefectus active, there is another controller. There can also be multiple Praefectus', making multiple controllers. If all Hives die, the Convergence will become extinct. Essentially a Hive is required, but there is no one single controller. The main objective of the Convergence is to spread, but they must protect their Hives at all costs. Pretty dissimilar from the other Hive Mind