Can anyone identify this?

[danjam97]

Hello,

There’s this white thing on my astraea snail shell, I’m sure I just saw it move.

can anyone identify it?

Thanks,

Daniel.

 

[Goby Bryant]

Can we get white light pics?

 

[EricR]

Yeah -- better pics would be good.
Is it soft and mobile like a flatworm or slug?
Are those "knobs" on it's back or is it just conforming to knobs on the snail shell?

Maybe get the snail into a little container and lift the UFO off to get an individual picture of it on its own.

 

[WheatToast]

Oyster is another possibility.

 

[danjam97]

Thanks for all your replies, it’s moved to an area that I can’t get at. I’ll wait until it moves and post with whiter light

 

[danjam97]

Yeah -- better pics would be good.
Is it soft and mobile like a flatworm or slug?
Are those "knobs" on it's back or is it just conforming to knobs on the snail shell?

Maybe get the snail into a little container and lift the UFO off to get an individual picture of it on its own.

Think it’s conforming to the snail shell. I’ll take it off when I can get at the snail

 

[EricR]

Think it’s conforming to the snail shell. I’ll take it off when I can get at the snail

If that's the case, I'd be worried that it might be some type of predatory flatworm (but just speculating).

...waiting to see it when you get it out and better pic -- good luck

 

[EeyoreIsMySpiritAnimal]

Possibly a fleshy limpet

 

[jabberwock]

Clam hat?

 

[CoralB]

Looks like a clam . You also have a starfish in the last pic

 

[jabberwock]

Looks like a clam . You also have a starfish in the last pic

Clam hat with a starfish broach!!!

 

[CoralB]

Clam hat with a starfish broach!!!

Nice!!!

 

[danjam97]

Managed to get it out the tank, it’s solid, I’m guessing it’s just part of the shell, strange. Thanks for all your help

 

[WheatToast]

Managed to get it out the tank, it’s solid, I’m guessing it’s just part of the shell, strange. Thanks for all your help

The growth doesn’t look very natural, in my opinion, so my guess is still on an oyster. Does it appear to have two shells?
The area (highlighted in green) sort of looks like the opening:

 

[danjam97]

The growth doesn’t look very natural, in my opinion, so my guess is still on an oyster. Does it appear to have two shells?
The area (highlighted in green) sort of looks like the opening:

Hi,

You’re right, I managed to get it out the tank, it’s very hard. Last few days I’ve seen the opening more clearly.

Is it harmful to the tank?

Thanks

 

[WheatToast]

Hi,

You’re right, I managed to get it out the tank, it’s very hard. Last few days I’ve seen the opening more clearly.

Is it harmful to the tank?

Thanks

These oysters and other NPS bivalves are harmless filter-feeders. While they feed on phytoplankton, which is usually lacking in reef systems, hitchhiker bivalves usually last for extended periods of time without this food and can continue to grow. Phytoplankton dosing is also an option and supports other filter-feeders.