Is it fungus?
My granules are much drier in a coco mix, nothing like that would grow since there is not enough moisture.
I think you just discovered something new!

Would there be any kind of salt concentration in that product I wonder?

Finally a sign of life.



Edit - After poking around, I have decided since there are no roots on any of the clay experiment subjects, to discontinue this experiment.  All cuttings have been transferred to grow bags with sand, like the rest.  Sand appears to wick better and I can't argue with results in the former wicking sand bucket experiment.  If they were common cuttings I might let them stay just to see but with these I don't just want to see. 

The elephant in the room is how are you going to get them out once they root?  With perlite you can float them out.  With this stuff and the sand you'll probably have to put the containers in a much larger water bath and tilt them on their sides.  Or do you have a better way in mind?

Charlie, thanks for trying! So now we know, from your hard work! : )

Frank from Bama