Any idea what these might be?

[corellianskies]

I have no idea what these things are. They're all over my skimmer, some are on the shells of my hermit crabs, and now I've got these fairly big ones on the walls of my tank. The ones in the pictures are slightly smaller than dime-sized. They seem to literally appear overnight and they don't move - they've been in their respective spots for weeks now. They have flat hard shells that are white to start and then turn green. Any insight is appreciated!

 

[saltyfilmfolks]

My guess is limpit. Can we see the top side?

 

[nautical_nathaniel]

+1 on possible limpit

 

[corellianskies]

My guess is limpit. Can we see the top side?

These aren't the best quality. I couldn't get a good angle on them. The green one is a little bigger than a penny.

 

[saltyfilmfolks]

These aren't the best quality. I couldn't get a good angle on them. The green one is a little bigger than a penny.

I would not be at all concerned about removing it and putting it in a dish.

 

[nautical_nathaniel]

Do they move around pretty fast? Limpets are pretty slow.

 

[corellianskies]

Do they move around pretty fast? Limpets are pretty slow.

They don't really move much at all, from what I've seen. Other than the initial "sudden" appearance, they pretty much stay put.

 

[nautical_nathaniel]

Your second set of pictures doesn't look like any limpet I have seen before, so I'm with @saltyfilmfolks and would say they need to be put in a cup and examined closer.

 

[corellianskies]

Your second set of pictures doesn't look like any limpet I have seen before, so I'm with @saltyfilmfolks and would say they need to be put in a cup and examined closer.

Here are a couple pulled out from the tank. Took pics of both top and under sides.

 

[saltyfilmfolks]

Those are beautiful. I like the corraline coming in on there.


I've not seen that exact one.
Let's #reefsquad and see if they or anyone else has.

 

[reeferfoxx]

Looks like dead snail caps?

 

[reeferfoxx]

Oh nevermind they are alive lol

 

[nautical_nathaniel]

There's a type of critter called the umbrella slugs that these guys might be in the same family as. The clearer one looks to be a juvenile since its shell is most likely still too thin to show any pigment yet.

 

[themcnertney]

Check out the hitch hikers guide...

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

I vote limpet

 

[SandJ]

Looks like a sea shell that is called a Painted Egg Cockle (or something close to that kind). But I think those are bivalves so that can't be it. But it has the same shell shape

 

[SandJ]

Try looking up slipper snail and see if that is it. I think I can see the little "pocket" that the snail is in and it has the right shape. Clear piece beside it is the operculum. We have dozens of these shells from the beach, never seen a live one though. Neat hitchhiker!

 

[Palyzoa]

I vote Limpit too

 

[Maritimer]

I think @SandJ has nailed it here. Wouldn't be surprised to find a little shelf midway inside that shell. These guys are often filter feeders, so the behavior fits as well - find a good spot, and lock in.

~Bruce

 

[EvsReef55]

Try looking up slipper snail and see if that is it. I think I can see the little "pocket" that the snail is in and it has the right shape. Clear piece beside it is the operculum. We have dozens of these shells from the beach, never seen a live one though. Neat hitchhiker!

Slipper snail was my first thought as well. I still have some empty shells if you’d like to see for comparison just let me know.