Kurt,
 
Nice try.  I actually do have one tid bit on terebra.  I have about 50
different species.  I never really concentrated on them but I have
always liked their delicate shape and nice color patterns.  Anyway, I
had always assumed they were strictly crawlers under the sand, leaving
their little trails as they went about their business.  A while back,
however, I found they can be quite active.  A friend (Bill Frank of the
Jacksonville Club) sent me some Terebra (Hastula) salleana.  As is often
the case with those of us who are landlocked, I had terebra from the
tropical Pacific but not from my own country.  As you all know, it is
often the very common shells that are the hardest to get hold of.
 
Well, back to the T. salleana.  In Bill's notes on the shells he stated
they had indeed been found buried in the sand.  But he went on (it was a
great data slip) to say they are seasonably common in the surf actually
"surfing" with their extended, winglike foot.  Actually, I believe Bill
called it an umbrella shaped foot.  This activity is thought to be
linked to coming into shallow waters to mate.
 
Does anyone know of other swimming terebra?  How about other swimming
seashells?  We all know about pecten and cavolina, and I have always
assumed bubble shells swim just by looking at their shape.  Are there
others?
 
Tom Eichhorst in New Mexico, USA