Strange Critter With Shell

[TanksJB]

See attached image for strange looking critter with a funny looking shell. It is not a crab or snail. I think the the dark hole on the end might be some kind of opening. It appears to have small feelers sticking out a short distance. The spine along its back has green stripes. This is from ocean rock over a year and half ago and it just now showed up. It blends in with the rock so look closely. The shell is probably half inch long or so. It might be some kind of filter feeder. Any thoughts would be appreciated.

 

[Dburr1014]

Maybe a conch? Sorta hard to see

 

[Reefer Reboot]

Can we get more pictures, preferably under white lights and in a separate container if possible?

 

[Wasabiroot]

Or from the side if possible. Does it move? Any visible "foot"?

 

[WheatToast]

Turkey wing shells (Arca zebra) and other bivalves are common hitchhikers on Floridian live rock and are harmless hitchhikers:

@LiverockRocks
@Gulf Live Rock

 

[TanksJB]

Or from the side if possible. Does it move? Any visible "foot"?

The critter doesn't move as far I can tell. I have been observing it for about a week. The shell seems a very intricate design and looks like darth vador or something weird. I guess the reason I missed it when it was smaller is because it blends in to the rock very well as you can tell. There is a raised spine down the middle with light green stripes. It would look much prettier if I removed it from the rock and took it out to photograph it or put it on the sand. Notice the deep curves and so on in its shell. Anyway, thanks for at least looking at it. I don't want to remove it because I think it will disappear. I don't know if bivalves have a shell like that because the first opening seems like it is filtering water but I would have to remove it to look for other openings. Besides, I don't imagine bivalves have shells like that. But I am no expert and some of you are so perhaps someone has seen something like this.

 

[TanksJB]

Turkey wing shells (Arca zebra) and other bivalves are common hitchhikers on Floridian live rock and are harmless hitchhikers:

@LiverockRocks
@Gulf Live Rock

The shell doesn't look anything like this to me. It is very uniform and intricate with deep curves.

 

[TanksJB]

Or from the side if possible. Does it move? Any visible "foot"?

At first I thought it was a crab but it does not have legs and doesn't move as far as I have observed. I am sure it is not a snail either which is what I originally thought and if so it is one that is different from anything I have ever seen. I think it must be a filter feeder. I have never seen any thing extend from the opining but I think there are short hairs or feelers or something in the opening.

 

[ISpeakForTheSeas]

The critter doesn't move as far I can tell. I have been observing it for about a week. The shell seems a very intricate design and looks like darth vador or something weird. I guess the reason I missed it when it was smaller is because it blends in to the rock very well as you can tell. There is a raised spine down the middle with light green stripes. It would look much prettier if I removed it from the rock and took it out to photograph it or put it on the sand. Notice the deep curves and so on in its shell. Anyway, thanks for at least looking at it. I don't want to remove it because I think it will disappear. I don't know if bivalves have a shell like that because the first opening seems like it is filtering water but I would have to remove it to look for other openings. Besides, I don't imagine bivalves have shells like that. But I am no expert and some of you are so perhaps someone has seen something like this.

I will agree that it doesn’t seem to be a turkey wing clam, but looking at your picture there, I would actually be very surprised if it isn’t a bivalve of some kind. I do agree that’s an interesting shell it has, so it shouldn’t be too terribly difficult to ID (though I would definitely need more pictures be able to have a chance of ID’ing it).

As I understand it, all (or almost all - I’m not sure about the carnivorous species) bivalves have two openings: the inhalant siphon (which takes water to filter in) and the exhalant siphon (which spits the filtered water/waste out). Geoduck clams are great ones to look at for interesting siphons, as they have both siphons running inside the same tube-like structure/opening (looking at it from the side, it looks like there’s just one tube, but when you looks at the tip of the tube directly, you can see that it’s actually two separate interior tubes sharing the same larger exterior tube casing, if that makes sense).

 

[WheatToast]

Just found this image of a very similar hitchhiking bivalve that was not conclusively identified; I'm starting to think that the openings of these bivalves are facing away from the camera, making identification difficult:
https://www.reef2reef.com/threads/hitchhikers-on-gulf-live-rock.330572/

 

[ISpeakForTheSeas]

I will agree that it doesn’t seem to be a turkey wing clam, but looking at your picture there, I would actually be very surprised if it isn’t a bivalve of some kind. I do agree that’s an interesting shell it has, so it shouldn’t be too terribly difficult to ID (though I would definitely need more pictures be able to have a chance of ID’ing it).

As I understand it, all (or almost all - I’m not sure about the carnivorous species) bivalves have two openings: the inhalant siphon (which takes water to filter in) and the exhalant siphon (which spits the filtered water/waste out). Geoduck clams are great ones to look at for interesting siphons, as they have both siphons running inside the same tube-like structure/opening (looking at it from the side, it looks like there’s just one tube, but when you looks at the tip of the tube directly, you can see that it’s actually two separate interior tubes sharing the same larger exterior tube casing, if that makes sense).

I do have to correct myself here: not all bivalves have siphons - oysters and scallops do not have siphons.