Tube like structure attached to the skeleton of my dead coral, please ID

[provia]

One of my Cynarina has unfortunately died. Upon checking everything including water parameters, lightings, etc, I didnt find any issue and the rest of the corals are all fine. What's concerning is the tube-like structure attached to the skeleton. There's another trachy in my tank that has this tube like structure as well, which I'm pretty sure the tubes weren't on it when the two corals came into the tank.

My initial suspection was tube worm. But I've never seen the net structure of the tube worm come out.

The death of this Cynarina was a surprise to me. It was fine the day before and it began to show the skeleton the next day if that helps.

 

[redfishbluefish]

Vermetid snails. They put out their sweeper tentacles at night. I'd be surprised if they did in your Cynarina.

 

[Argentum]

Vermetid snails. They put out their sweeper tentacles at night. I'd be surprised if they did in your Cynarina.

Agreed.