An unexpected find during my Chincoteague expedition last October* was a couple of shells of the European land snail Helix aspersa (= Cornu aspersum). Both shells, one adult and the other juvenile, were attached to the back wall of a small commercial building. Below is an in situ picture of the juvenile shell.
The adult shell was empty, but the juvenile shell still had the remains of its former occupant. You can read the details in this paper that just came out in the current issue of Triton.
I have no idea how the snails had been introduced to that location where there has also been, for the past several years, a vigorous colony of another alien snail Cernuella cisalpina. I will probably go back to Chincoteague in the future and check out the snails in that particular location and elsewhere.
Stories from Chincoteague are here, here, here, here, here, .