Concrete Pier In Footing
Whenever you run into a situation where a
concrete pier is sticking out of a foundation, there's a good chance
that there was a patio here before.
This will also give you clues that the room addition was not permitted and could require a new foundation.
Over the years I have ran into situations like this and there is very little you can do about them.
You're in between a rock and a hard place, if you call the building department to ask them some questions about the room addition, you could end up tearing it down or bringing it up to code.
If you're thinking about buying a house with this situation, this is going to be one of those problems that will require a little bit of thought.