Need help identifying critter

[bfyfe4]

I need help identifying a critter living in one of my new coral pickups. I’m new to the hobby so I have lots to learn and lots to see. Just curious if it’s something to be concerned about and what exactly it is because I want to know what everything in my tank is.
The first 2 pics are out of water and the last 2 are in the water. Haven’t been able to get a good picture of it yet but it seems to open up inside and has something sticking out.
Thanks in advance

 

[cdemoss01]

Looks like a barnacle. does it move?

 

[bfyfe4]

Looks like a barnacle. does it move?

The shell (sorry not sure if that’s right) moves in and out of the hole. It looks like it an open tube inside the hole when I use a flashlight to look in

 

[tbrown]

+1 barnacle. Does it look like a feather waving in and out when it's open?

 

[bfyfe4]

+1 barnacle. Does it look like a feather waving in and out when it's open?

I have not seen anything like a feather waving yet. This morning when I put a flashlight on it, it looked like a black/dark red lining inside of the hole. Could not see any of the shell

 

[bfyfe4]

Not a great picture but this is what it looked like this morning before lights came on. Little black/dark red thing pulled in when I put a flashlight on it

 

[Savage Henry]

It’s a harmless clam. You’re lucky to have it. If it dies it will leave a perfect hole with smooth walls for a blenny.

The black part is when the shell opens.

 

[Savage Henry]

Also, the one I’ve had inside holes in my live rock tend to stay there, but the ones I have that are stuck to rock can move.

I’ve just attached a picture of a free-moving one I have.

They don’t look anything special.

 

[bfyfe4]

T

It’s a harmless clam. You’re lucky to have it. If it dies it will leave a perfect hole with smooth walls for a blenny.

The black part is when the shell opens.

Also, the one I’ve had inside holes in my live rock tend to stay there, but the ones I have that are stuck to rock can move.

I’ve just attached a picture of a free-moving one I have.

They don’t look anything special.

Thank you very much. I can sleep again tonight. Appreciate the picture too. That’s so cool