Dear all: take a look at this picture and see if you recognize the shells.

http://petrelnet.oglethorpe.edu/division3/Faculty/jcramer/jcramer.htm

I found the auger-like stuff at Lake Cunningham, New Providence Isl. near
Nassau.  Paul Mikkelsen and Harry Lee both guessed Cerithidea scalariformis
from my description a few weeks back but they're nothing like my
scalariformis.  I believe the lake is freshwater - didn't sample it.
The small shells are land snails from bushes around our resort at South
Ocean Beach on New Providence Isl.