Now this won't work too well for a whole mess of large shells, but
you might try it for a few smaller ones. I've heard of just putting
them out by an ant hill and covering them with an old piece of cloth
(protection from the sun). What you have to do is determine whether
your ants are carnivores or herbivores. Some are both.
  If your ants have been properly styarved, they will do a quick and
thurough job. Then you have to figure out how to get rid of the ants
before company comes.
       Art