Curiosity is always appreciated.
My idea is that each individual of the Oual is a hive mind. The nexus is the "main" part in the sense that it does a lot of coordination and higher social functions and steering, but not all thinking is necessarily done in the nexus. The foci can, and do, think for themselves in some sense, but mostly for baser functions such as motor control, interpretation of the senses, and positional memory.
The way I intend Oual to be is a hive mind of unequal parts. They do not form a single species-wide consciousness, but instead each "individual" is a hive mind, and they cooperate the same way most other species do: by talking to each other.
Does that make sense to you?
PS. I added a note on the "life span" of foci, see the diff.