I'm trying to describe something that has been spontaneously established a while ago (without permission) but has since then became accepted (though not authorized).
This applies to a fireplace / campfire that someone a couple of years ago put in place with some stones and that still exists though is not officially recognized.
Ideally I would like to describe the aspect of spontaneity and unofficial in as short a sentence as possible.
I had some ideas: A spontaneous fireplace (misses that it is not authorized). An unauthorized / unofficial fireplace (misses spontaneity). A tolerated fireplace (still same issue).