Found in my sump, what is it?

[Jason Jones]

I was cleaning my sponge filter and found three of these.
Tank has been up for over a year and my others have been running two or three. I have never seen these.
About the size of your thumbnail, appears to have a mouth, has a very firm body, two were embedded into the sponge and one was firmly attached to the acrylic holder.
When I rinsed under fresh water it seemed to retract some.

 

[Alexreefer]

No idea lets get some help. #reefsquad

 

[NY_Caveman]

Looks like snails. Do they move like that? I thought a stomatella in a couple.

EDIT: can you get one alone?

 

[davocean]

Not sure, maybe check here.

https://www.lionfishlair.com/hitchhikers-guide/

 

[Jason Jones]

Looks like snails. Do they move like that? I thought a stomatella in a couple.

EDIT: can you get one alone?

That is one. I thought it was just chunks of algae or something so started rinsing. After that I had the epiphany to take a picture and try and see what it might be.

 

[NY_Caveman]

Got it. So it does not move. Just retracted. Now I am wondering if it is a Tunicate. Was it in the dark? Low flow?

 

[Jason Jones]

Got it. So it does not move. Just retracted. Now I am wondering if it is a Tunicate. Was it in the dark? Low flow?

Dark but high flow. I run triton and it was in the baffle between skimmer and return pump.
It might not have intended to be there and just got swept away.
I have a few stomatella in my other tank but the entire outside of this is a slimy flesh. The “crunchy” part was under the flesh.