I had them in Italy (where they are not common, either). In Venice they are called capelonghe (cah-peh-LOAN-gay), elsewhere in Italy they are known as cannolicchi (cahn-noh-LEEK-kee). I did have them in the shell, simply prepared in Venice. Recommended for the real seafood lover.
If I can find out where they've cleverly concealed the Massachusetts razor clams in the Boston area, I'll make them and post the recipe.