Question

A snail’s shell is formed from its ________.
A.mantle
B.foot
C.radula
D.notochord

Answer 1

I'm going to go with radula. Notochord should be neuro, foot is the attachment to the outside world, and for some reason I think the mantle is also related to the outside/foot. I'm googling now:

Nooooo! I am wrong! "The outer edge of its mantle continuously adds new shell at this opening. "

It's the mantle. http://www.scientificamerican.com/article.cfm?id=how-are-seashells-created