Hi everyone, I am new to the forum. However, I've had a reef tank for over a year now. For about 6-8 months, I had NOTHING but 2 clownfish, a yellow tang, a lawnmower Benny. I bought live sand and live rock at a local saltwater tank store called Seafari. I recently moved and needed to take out a lot of water to move the tank. So when I refilled my tank, I guess I was really really needing a water change and lots of little things began to grow. Some of these I have identified as feather duster worms and coralline algae. (Correct me if I'm wrong.) here are two pictures I took of a few things I need help identifying. The photo with the clownfish: The yellow stain in/on the rock. There are two of them. And the white sponge looking thing. what are they and are they Bad?
On the second picture, what are those black spots? They look squishy but at the same time look rock hard. I'm scared to touch them. (Sorry I couldn't submit better quality pictures.)