Not only sea turtles turn up in Europe. Think of Cymatiidae (more than 5
species) and Epitoniidae (Opalia crenata, Gyroscala lamellosa) which live on
both sides of the Atlantic and have probably been moved to Europe by the
Gulf Stream.
 
Concerning the shells in the Florida panhandle: As an analogy: The last ten
years in Europe were quite warm and a few species with a southern origin
were found in more northern locations.
 
Also concerning the findings of Cypraea moneta, annulus in Europe. There are
probably two sources for these:
 
1) "Basket" shells
2) Old shells which wash out of Dutch and British merchant ship wrecks (very
rare). The shells were acquired bij the Dutch VOC in Indonesia (the former
Dutch East Indies) and the Maldives and were used for slave trading in West
Africa by the Dutch WIC during the 17th and 18th century. (VOC and WIC were
Dutch trading companies). The British followed probably a strategy like that
mentioned above.
 
greetings from The Netherlands
Erick