This Friday I’ve decided to give you something alive and without any bones, for a change:
So two three questions this week, what is this massive mollusc, what does it eat and do you think it can fit all that body into its shell?
Feel free to ask questions in the comments section below – and for those of you with a good knowledge of marine invertebrates I may have to white-out your answers if you get them correct too quickly.
Best of luck!
Zygoma 
Well, I guess I’ll get the ball rolling.
It’s a marine gastropod, that much is certain.
I have to say, I’ve not seen anything quite like this, and I’ve seen a fair bit. It looks somewhere between a giant abalone and a giant limpet!
I’d say it probably can fit in it’s shell, and like most coast gastropods, is likely to be detritivorous.
But, Jim, to use technical language this creature has a whorly shell unlike the limpet or the abelone!
I found a handy ident key which leads me to a Lymnaeidae, which is non-marine gastropod.
Is it lymnaeidae, a pond snail? I’m struggling to narrow it down beyond that stagnalis seems to have too pointy a shell.
I shall make a wild stab in the dark and claim the squidgy bits don’t all fit inside the shell.
You’re both right in that it’s a gastropod, but beyond that you’re both wrong about what it is.
One of you is right about whether it can fit inside the shell.
No-one has got the diet right.
Yet.
So much for bleedin’ identification keys!
Searching for carnivorous snails seems to get me some candidates. A moon snail would seem rather possible, they eat other molluscs. I get the impression the mantle is not retractable.
Can you eat it and if so, what does it taste like?
You can eat it, but I’ve not tried it, so I’m not sure what it tastes like! I bet it’d be really rubbery though.
I’m going for Giant Atlantic Cockle…
It only has one valve, so it’s not one of those I’m afraid!
Well it obviously doesn’t eat flesh 🙂
If it could fit inside the shell then surely it would retreat there on being picked up?
Is it a sea creature or freshwater?
You would have thought so!
It lives in the sea.
Well, didn’t say it was either, just like a fusion of the two. Giant abalone do have a slightly whorled spire, though obviously not as pronounced as this.
However, it is of course a Moon Snail, and the ugly brutes eat clams and mussels.
Which side of the Atlantic was this found?
It wasn’t found in the Atlantic – it’s Pacific!
…and I do recall handling one, though definitely not as large, as I distinctly recall the large effusion of goop as it retreats into its shell.
Interesting, so is it Lewis’ Moon Snail, Polinices lewisii?
Looking at the photos, it is clearly a sort of sea snail, giant style, found on a seashore. Does it eat coral? I would imagine it does fit in its shell.
Not a coral eating beastie – it lives in marine muds, generally in quite cool waters.