Spiral worm thing?

[LovesDogs_CatsRokay]

anyone know what this is? It’s shell is hard and kind of reddish brown. The white stuff coming from the left edge of the picture is a sponge I believe.

 

[Big G]

Looks like a Vermetid (Tube Snail, Gastropod)
These things start out with just one or two threads and then end up casting out a pretty good sized mucous net that can irritate corals.

 

[LovesDogs_CatsRokay]

Ah okay. I thought vermetids were tiny little things. I guess they just start out tiny. Thanks!

 

[Big G]

Ah okay. I thought vermetids were tiny little things. I guess they just start out tiny. Thanks!

Other possible is that it's a Polychaete - Chaetopterid/Spionid (Tube Worm) These are a bit bigger in size.
Here's a good link to help you keep an eye on your critters and help decide if treatment is needed https://www.lionfishlair.com/hitchhikers-guide/

 

[KJ]

Vermetid snail.