Originally Posted by adacaro
they are like tree roots growing all over, and they are like sponge.
If it looks like a sponge, it normally is. There are branching root type sponges, I had them in my seahorse tank and the lfs
I go to has two tanks they keep the lights off on to propagate them. Not sure why except that sponges are great filters.
Anyway, they seem to love low light/high nutrient areas. Mine went away on it's own, yours may as well or you may want to cut them out if they get to invasive.