Long clear thread with white ball on coral frag

[Lebski]

Hey guys, I’m quite new to corals in general and was given these frags by a friend, they’ve been fine for the first 2-3 weeks. However, I have just noticed these long threads about half an inch with a white ball on the end of them.
I have tried to take some photos, I hope they are clear enough. The coral frags were dipped at my friends house and left in his QT tank for a while as I don’t have another tank.

But what are these? I assume they are some kind of pest.

Any help would be greatly appreciated.

 

[Lebski]

Also, just to note I have spent 2-3 hours searching before posting but no luck on the ID ☹

 

[ChiCity]

those look like the chalice’s sweepers to me

 

[Lebski]

those look like the chalice’s sweepers to me

Ooo after looking those up I think you may be right! Thank you!! I found a digitate hydroid on my GSP from my LFS and pulled it out with tweezers so was concerned this could’ve been more of them

 

[Gtinnel]

Ooo after looking those up I think you may be right! Thank you!! I found a digitate hydroid on my GSP from my LFS and pulled it out with tweezers so was concerned this could’ve been more of them

It's the sweeper tentacles from the chalice not hydroids. I believe that's a Hollywood Stunner and they have very long aggressive sweeper tentacles, so be careful what you put it near. I just had to move a rock covered in GSP in my tank because it was getting stung from my large chalice.