Critter id

[Zoacoral]

Hi, I got something in my rocks that I'm unsure if what it is. I got the rock from kpaquatics more then a year ago. I just noticed this thing. If I take a turkey battery and blaster it, it shoots back into the rock. I pulled the rock out to see if I could get it out, no luck. Any ideas?

 

[RedFrog211]

Might need to see more before giving an ID. I’m thinking a type of mollusk?