What the heck is this?

[Cthulukelele]

Started growing on a shell I added for hermits

 

[James M]

Hard to tell from the pic

 

[Cthulukelele]

This pic is pretty much exactly what it looks like in person. It hasn't moved but has maybe quintupled in size

 

[redfishbluefish]

@KJ #Reefsquad

 

[TheEngineer]

Vermetid snail?

 

[Jason mack]

Maybe a sort of limpet...??

 

[Cthulukelele]

Vermetid snail?

It doesn't seem to have an opening or do any slime trailing.

Maybe a sort of limpet...??

Some weird limpet was kinda my guess , but it has grown quite substantially and hasn't moved

 

[Bob Loblaw]

Google slipper limpet.

 

[Cthulukelele]

Google slipper limpet.

That looks pretty dang close! Friend or foe?

 

[Bob Loblaw]

Harmless.

 

[saltyhog]

Man, I don't know! If it was a limpet it wouldn't just sit in the same spot would it? How long has it taken to increase in size 4 fold?

 

[Cthulukelele]

Man, I don't know! If it was a limpet it wouldn't just sit in the same spot would it? How long has it taken to increase in size 4 fold?

Maybe 3-4 months?

 

[DSC reef]

Have to wait and see if it grows. It looks like a vermetid snail building up.

 

[reef lover]

If its a slipper limpet it will not move but stay on its host and eat what algae is available as the host moves...never seen one on an empty shell .

 

[Lovemyreef2015]

I'm going to say vermetid snail

 

[Cthulukelele]

I'm going to say vermetid snail

Maybe so! It is giant! That bottom part is maybe like the size of a thumbnail