Help black cotton

What is this growing on my fake plants???

black algae, just wash the plants under tap water. if it doesn't come off, soak the plastic plants in bleach for 15 minutes then rinse really well under tap water.

I had loads of that stuff on a piece of driftwood that i added to my main tank. It started of white like cotton wool.
I boiled it twice before adding, rubbed it & boiled it again & it still came back, Then i got a Nerite Snail, now its taken care of ?