Apologies in advance for posting something so gross, but I'm having the unenviable task of cleaning this disgusting thing but have no idea what the black is. I've not actually seen it, only this picture - so don't quite know what to go armed with product wise. Vinegar/baking soda? Bleach? Coca Cola
I'm aware of black accumulating in toilets at the water line when they're not cleaned regularly, but not all the way up the bowl itself.
Can anyone help - is it mould or something?