Is this part of the frogspawn or something else?

[Bearchumjs]

Hey guys. I got a frogspawn just over a week ago. Ever since then I've been wondering what this is and if it is actually a part of the coral itself or something else. In the second picture I hope you can see the creature thing that is popping out. It comes out and goes back in. If you get too close to the opening it closes up tight. So is this how frogspawns eat? I couldn't find anything about it on the computer so I'm seeing if anyone here knows.

PS: (picture one was shortly after I got it and the frogspawn was still adjusting)

 

[ccCapt]

That's proabably a vermetid snail.
Snails That Worm Their Way Into Tanks by Ronald L. Shimek, Ph.D. - Reefkeeping.com

 

[Bearchumjs]

That's proabably a vermetid snail.
Snails That Worm Their Way Into Tanks by Ronald L. Shimek, Ph.D. - Reefkeeping.com

No, it's not one of those. It doesn't match the description.

As I was racking my brain suddenly I thought- barnacle! I believe that's what it is.