So... Post the most obscure musical genres (metal related or not) you have ever stumbled upon.

No lyrical based genres allowed. A genre based solely on the lyrical themes is not a new musical genre. Also please don't post those genres which already exist but have just another tag incorporated, like calling underground rap a subgenre of rap when they are really literally the same thing.
Also some examples of the genre posted would be most welcome.

So please..? I'm looking forward for the most obscure ones

This is not really a very obscure genre, but since I came across this good article and since people don't seem to have a very good idea about what slowcore is, I'll share it here. It's one of those "hard to define but you know it when you hear it" kind of genres, with a stellar track record. I mean, 80% of the bands in this list are really good:
Slowcore: A Brief Timeline

Harsh noise wall, extratone, splittercore, gabber, aggrotech, power electronics, death industrial... I'm not sure these are necessarily the most underground genres ever but they for sure aren't the most well known ones