Look up 'nostoc'. A bacterium, believe it or not, not a fungus or a mould.

it is Nostoc and it is a cyanobacterium. treatment with ferrous sulphate is recommended. improve the drainage in the area if you can. remove as much as the visible stuff as you can. it is harmless if that is any consolation.

seems to develop in the drip zone of trees and shrubs.

Are you sure that cyanobacteria is harmless, Seaburngirl? Is this not what is commonly known as blue-green algae. It is more usually associated with lochs and lakes and can cause severe stomach upsets and cramps in humans and animals, dogs, can die from ingesting it. In Scotland all waterbodies used for watersports are tested every week in summer for the algae and several have been closed. Seafood harvesting has also been halted in some sea lochs because of the same.

there are many species of BG algae and yes some do cause problems BA. this species doesn't live in water bodies and according to the RHS pose no health risks.

'K.

I thought the same as you Bulba, but some years ago I went for a meal at some Chinese friends. One of the dishes was something called Fat Choi. Someone there told me that this was Nostoc which I was surprised to hear. Apparently the Chinese consume lots of it at the Chinese New Year because Fat Choi sounds like riches, wealth, or something similar in Chinese. I think I'll stick with chow Mein.

Amazing what we tap into on this site! All from a patch of greenish gooey stuff on a rock garden!

Many thanks,my wife has been very woried about it but now we know what it is we can start to get rid of it and improve the soil to help prevent recurrence.
Many thanks again.
Regards Ramrod