Maurizio,  I've been collecting and calling it Jaspidella jaspidea
(Gmelin, 1791) for many many years now, and never thought anything about
it.  It's more like an olivella than a olive.  I'm sure you will get a
more intelligent and scientific answer than this.  Maybe Phil Poland
will tell you what happens when you have no where to hold a shell when
you are screening in chest deep water and put one in your mouth, and
then again he may not want to say.
 
Bob Lipe
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