What's this??

Morning all

Would really appreciate you valued opinions on what this stuff is (pics enclosed) and how I deal with it. It's very black (I initially thought it was dirty oil) and seems to have an almost felt-like texture.

Many thanks

Gary

 

Hmmm. Looks like some sort of fungus but your description of "felt-like" is puzzling.
Is there much of it? You could try giving the area a good scarifying to break it up. That should certainly do no harm and you can always go thermonuclear later....