Bristle Worms

[Jinx]

Not sure about the worm, but it doesn't look like anything harmful that I know of. Do you know where your rock came from? I mean, what country...That can help you/us with the I.D.

To be absolutely honest no I can't. The LFS owner I bought the tank from was relocating his store. I live near Panama City here in Florida. Many pet shops kennel pets and tanks for the seasonal residents. My tank was an abandoned tank by its owner. We call them "snow birds" down here because they migrate south when it gets cold up north.
All I paided for the BioCube and all the corals plus muck was the unpaid kennel fees.

 

[Jinx]

I had also noticed a worm type thing that extends from a hole that wiggled and swayed similar to an anemone tentacle. I couldn't get a good look or a pic but its very smooth in texture, dark in color, and retracts back into the hole with any light source. I see more than one but the largest at the point I saw it extending was about 2".

I hope maybe I described it enough

 

[rockkfish]

could the tank have copper residue in it from previous owner?

 

[mr_X]

could the tank have copper residue in it from previous owner?

Not if bristle worms are living in it.

 

[Jinx]

could the tank have copper residue in it from previous owner?

I have live plants, macro algae, growing very very well. My experience with copper and live plants is it ends badly for the plants. It makes them less fertile which it not an issue in my tank. I just recently had to give fern and grape macro a hair cut. New growth loving the space.