Pest in chalice coral?

[SchrutesReefs]

I posted this in the general sps thread, but it didn’t get much attention. Maybe this forum is better suited.
I received this bubblegum chalice from an auction at my lfs, I dipped it in Revive before putting it my tank. There is a feather type creature that pops out and retracts every few seconds. This does not look like any type of feeder tentacles from the chalice coral itself. Possibly from the rock it was attached to?

pic attached and here is the link to a quick clip

 

[G Santana]

Looks like you have a barnacle in that puppy

 

[SchrutesReefs]

Would you consider that good or bad?

 

[G Santana]

Would you consider that good or bad?

No worries just a harmless filter feeder.

 

[SchrutesReefs]

That’s good to know. Thought it was odd that it had appeared in the middle of the chalice.