Cattleya - with unid fungus/mold on root
 

I have recognized that the turf under some of my catts which are in the same pot. It worries me a lot, but I did not see any major issue on the leafs or in general on the roots. Can somebody tell me what is this?
I was thinking snow mold, but I am not really sure.
Also what is the best to fight this off.
the roots are kept relatively well aired and not overly humid
many thanks
Baron

Many orchid seedlings or meristems are propagated in small plugs of sphagnum moss. The plugs are in large plastic trays, with holes the size of the moss plug.

It looks like the plug is remaining at the base of your plant. The moss eventually rots, and mold grows on it.

Some people carefully remove the sphagnum plugs from their plants when repotting. Others do not. If your plant is otherwise healthy, I would not worry about it.