I visit the “i love shelling” blog from time to time to see what vacationers to Sanibel Island, and the writer herself, have been finding along the Gulf Coast beach.
On one visit I found a chart for sale to identify shells. But now the link no longer works… so…..
So, instead I will direct you to her page about identifying seashells common to the area.
I also have a page about Collecting Seashells and the types of shells you may find.