Hee Hee!  Cypraea turdus may have nothing to do with excrement, turds,
or doo-doo - but Cypraea stercoraria actually does!  The Latin noun
stercus and the prefix stercor- refer to excrement, as does the
english adjective stercoraceous.  Apparently that's what Linnaeus
thought this cowrie looked like!  And Linnaeus was not one to hold
back when he thought a species resembled something, be it a part of
the human anatomy, or even a pile of dung.
 
:-)  Paul M.