James,

Fossil nerites can be quite rare. Nearshore sediments tend to be eroded
rather than buried, so their preservation potential is low. The occasional
specimen can be preserved in nearby environments that are more easily
preserved but outside their usual range. Or, conceivably, they might be
preserved in all their millions in one layer, but I've never come across a
record of that.

Andrew K. Rindsberg
Geological Survey of Alabama