Becca, that is a completly different animal. It is a Bivale snail,
Berthelinia sp but it is also a sapsucker like the other.
I need a better pic. The closest thing I can find is a
Tylodina sp And I do not buy that at all. It looks like Lynn's, only yellow. And I'l bet it is a sapsucker due to the big 'Antlers" and the way it sits. It should be easy to ID as yellow is kinda rare in seaslugs. I can not find anything yet and I have 2 books just on slugs and one has 1,000 pic's of them.
Tylodina - Google Image Search