Whats living in my Acropora?

[Holst]

Hi everyone.
What is living in my acro.? When i near it with my turkeybaster it retracts into the acro..
Sorry for the bad picture.. its just two tentacles Tjaa appears..

 

[X-37B]

Looks like spionid worms. I had them consume an entire frag a few years ago.
Some say they are harmless and many are found in the sandbed.
Mine were not harmless.

 

[Holst]

Looks like spionid worms. I had them consume an entire frag a few years ago.
Some say they are harmless and many are found in the sandbed.
Mine were not harmless.

Okay, thank you !
I glued it and another one, and will be observing the corals closely

 

[Rtaylor]

Vermatid worm