As Clanad indicates above, phobia-names are made up from the appropriate Greek root-word. On that basis - 'snail' being 'saligkari' - I suggest 'saligkariphobia' for the snail aspect at least.
The first place I looked was http://www.phobialist.com/
but I think Clanad beat me too it! (Incidentally, his suggestions of Blennophobia or Myxophobia both mean 'fear of slime').
A bit more searching, however, led me to this site: http://www.shagtech.com/features/phobias.html
Here the term MOLLUSCOPHOBIA is coined for the fear of slugs & snails. (There is also a claim that the actor Steve Martin suffers from it!)