Weird hitchhiker in my live rock

[jehanjindal]

There's this weird hitchhiker in my live rock , there are atleast 4 of them living inside the holes of my rock and i tried to pull one of them out to see but i couldn't they were anchored in so tightly , ID anyone?. Images attached below

 

[Gman83]

Where did you get your rocks from? If TBS they have a hitchhiker guide that might help.

I have no idea sorry.

 

[threebuoys]

aptasia?