I've been keeping a brackish puffer tank for about 2 years now. I have a school of Mollies that keep the glass totally algae free. Over the last 3-4 months these black spores have populated on one piece of driftwood and seems to be spreading. That specific wood has been in my tanks for almost a decade. I'm not concerned if it is beard algae...I actually think it would be cool if it grew and flowed like hair. I just have not seen anything that looks like this online.