That is an old picture. The java moss was put on the pot originally to use as a cave then the moss covered it and kept going. There is a pic around here somewhere that shows the same moss and it had filled that 10G tank

. Never had any problems. I have had the moss grow through the netting and just left it without any problems and have left it on others until the moss is attached and gently removed the netting. Never had a problem in the tanks I've used it in but do rinse it in cool water to remove any dust that might be on it.
Carol