Funnily enough, I've just signed on to trawl the internet to update my snail planning.
There's a lovely book called Archie's snail, that a boy finds and takes inside...it escapes and travels around the room, in and out, over and under.
We've also used Matisse "The Snail" as a starting point. It's interesting to see who thinks they can see the snail or otherwise.
Talking about spirals....you could set up a technology experiment to make a spiral, using sand or a felt tip pen, swinging pendulum style
Paper plate snails are great too.
I've got a heap more stuff.....if only I could find my file!