A little history about the tank, I bought this setup and tank from someone about 2 months ago. None of the live rock are new, but the tank was very poorly maintained previously with no water changes. I've noticed recently I've had some weird growth on the live rocks and was wondering if someone can help identify what it is and if its harmful to anything inside my tank. It's growing on the rock some what hanging off it too. There is also a dark red/ black / purple spot on the edge of the rock it's hard to capture since it almost looks it's a shadow in pictures. There is also a little fluffy looking thing that just started growing out of it but its too small to be seen.