Bob,

The Cymatium parthenopeum I found on a sandflat in North Carolina was doing
some strange behavior after capture.

It was slowly raising its shell and then suddenly bringing the shell
downwards, in a violent motion. It repeated this several times. It was doing
this exposed on the sand at water's edge with ample salt water to refresh
it. It had previously been in my bucket for an hour or so.

Maybe this is a reflexive behavior designed to possibly dislodge any
predator's intruding anatomy. Beats me.

David Kirsh
Durham, NC