Mold on coco surface. Mycelium?

I’d scape off dently so it doesn’t spread and to prevent you could water plants after the top of soil has gone dry and crusty looking . More air flow will help create - nice crust and plants should start eating up more water so you can perform a really good sponge effect with your soil / root ball system . If you thing you have plenty of air flow reduce your watering frequencies I

Mycelium goes away fastly enough and looks like spider web u could say...and it's not harmful for the plant, it's normal fungi created from the reaction of the bacteria inside of your medium (not chemist, don't shoot me if using wrong terms) Since the spot is very small you could just remove it to be sure.