As described in the History of our Census, Auditor appears to many of us to sit in a featureless room, behind a desk with a type writer or calculator or computer terminal in front of it that has tubes or wires running from it to the walls. When we ask it a question, it hands us a sheet of paper with a number on it. Or a "yes" or a "no". It appears to those of us who have seen it as a figure in a suit with a completely blurred out head.
This is what it's like to actually visit its headspace and interact with it directly. And obviously, these visualizations are our own interpretations of its self-schema. Which is especially evident that, like with everyone else in our system, it looks slightly different to each one of us who visits it.
When receiving communications from the Auditor while conscious, it either sends signals to small muscle movements of our neck to urge our head to either nod or shake in response to questions, or it sends a jarring visual flash of a number on a white field (much like a piece of paper).
It can also flood the system with an emotion. One emotion. Satisfaction. Which it does when we choose to believe its reports.
Apparently what the Auditor does is count things. And primarily it counts our population. It cannot differentiate between subtle categories very well, however. So, it cannot tell the difference between a new Liaison and someone like Phage or Eh, for instance. It also takes quite a bit of effort for it to send information to the Bridge, and its messages lose accuracy the longer we question it within a short period of time. We hope to learn how to hone our skills of communicating with it over time, so that we can use it more often and more frequently, and to run some more experiments to learn its limits. But we have been distracted by other things so far, and also do not want to burn out our connection to it.
We consider it a part, rather than a headmate, as it does not count itself as part of our population.