Worm living inside hammer coral skeleton?

[Alyssalaurente]

Hello! I’ve noticed this brown fuzzy looking thing popping in and out of a hole in my hammer coral skeleton (bottom left)I made sure to dip the coral before adding it to my tank, but I guess whatever it is, wasn’t phased by the dip. Any ideas what this could be? Is it harmless, harmful? Hammer coral has been opening up fine and looks healthy so far. Please let me know your thoughts. Thanks!

Here is a video

 

[Alyssalaurente]

Here is an image if the video is not opening up

 

[MERKEY]

Looks like it could be a feather duster.

 

[terraincognita]

Here is an image if the video is not opening up

need a better photo, could be feather duster, aiptasia, or a vermitid from this photo, honestly I just can't see it.

 

[KingTideCorals]

Hard to tell from photo! Hoping for mini feather duster and not some bad unwanted pest. Could do another dip cycle on it!