I think the Abyssal plains in my theory deep in the Earth's oceans have underwater bases hidden from research divers' line of sight filled with Abyssals in the Abyssal zone depth. In them, they function as some sort of Command Center that have a network of nodes connecting to other plains across continents to communicate with their commanders, the nodes we been using to hunt them down on a regular basis. They use sunken mythological civilizations as hideouts, so that KanMusu fleets cannot easily find them, and only a research prototype sub-class can reach them in the far future.
To this day, we still don't know who is really behind managing such a huge chain of Abyssal bases that we never get to see on the surface, but taking them out one by one will surely reduce their reproduction rates and disrupt communications.
An example of a normal ocean floor (Controlled by KanMusu, anyone can freely sail in these waters)
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An example of a corrupted ocean floor (Controlled by Abyssals, only sparkled, highly determined KanMusu ships can withstand equipment and morale damage in these waters, can expand if let alone for too long)
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