Hi my friend - I think that your examples do not correspond either to C. batillarieformis nor to C. bifasciata, but rather I would think Clypeomorus inflata or C. pellucida, the latter typical of mangroves, although according to the revision of Houbrick these two species would not be present in your area. You have the revision of the Genus Clypeomorus of Houbrick? If you do not have to tell me that I sent you. See the pictures. Best, Gianluigi