Lucifer has started to self-seed in my garden. It looks the same as the parent. Noticed flowers this year which taken about 2 years. So if you have excess seeds maybe also just try casting some around, you may be lucky!
I have exactly this growing on a concrete path. It is a real pain and very slippery to walk on. I thought it was a slimemould but have been unable to identify the actual species- I agree with you it doesn't look like any of the pictures I can find on the 'net. I am scraping it off with a spade at the moment but if you find a better way to exterminate it I would be grateful to know.