Hi David,

Your shell appears to be a Latirus.  The general shape and operculum, as
well as the habitat in which it was collected, support that idea, IMHO.
The combination of broad body whorl, heavily nodulose shoulder,
indistinctly lirate aperture, spirally ridged base, and slightly
reflected canal suggest Latirus belcheri (Reeve, 1847).  Also, although
the shell appears somewhat encrusted, I think I can see some of the
characteristic dark axial streaks of L. belcheri showing through on the
anterior end.  That's my best guess.

Regards,
Paul M.