Sorry Tom BUT you wrote
"I have always thought the Conus cedonulli complex left a relative on the
other side of the land bridge by the name of Conus brunneus"
, it's conus archon not brunneus, conus archon (Broderip 1833) is what's
considered a conger ? brunneus is more like regius. good link though.
about the unionidae tempting fish with the minnow like larval sack , some
fish have developed a type of mucous to ward off potential parisitic larva.
mark