That pink and white combination is called alabastro. It's a very specific and collectable sort of glass.
You might get a bit further using that word.
I'm really not at all sure it is related to the clear glass one, which looks moulded, rather than hot worked, as the coloured one is. I know they're basically the same shape, even down to the flat part of the centre of the shell and the puddle of slime behind, but they
do look like completely different methods of production.
The eye stalks are very different.

Unless the clear snail is not moulded, but was perhaps acid treated to give that surface, which might be something scarce, called corroso. I haven't seen enough corroso to be able to identify it well.
There was much excitement here in '05, when somebody found a rare corroso hippo.
But I don't think that's what your clear snail is.
If it is, I have a hat I will eat.
But I'll keep my fingers crossed, for your sake, that I will be eating my hat.
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