Shells from a long distance away?

[dave r]

Kenny, when you say 'shells from other areas' do you mean in the sea alive or on land or dead? Some species are imported for food and the shells thrown away. If the shells are very old they could be sub-fossil species that occurred there many years ago but no longer do.
Some shells can travel a very long way. If they have larvae that are planktonic they can drift on the curents for many miles. A few species are almost worldwide in distribution because of this dispersion method. As adults they don't tend to travel very far at all, a matter of yards even!
Dave