I suppose they are not snakes.

And they grow out of a flower, too; and it has a stalk, jointed, too, as plants sometimes are; and as fishes' backbones are too.

Is it a petrified plant or flower?
No; though I do not deny that it looks like one.

The creature most akin to it which you ever saw is a star-fish.
What! one of the red star-fishes which one finds on the beach?
Its arms are not branched.
No.

But there are star-fishes with branched arms still in the sea.