Hi Don,
I was unable to open your pictures on my computer at work for some reason,
but I'm able to open them here at home.  Pretty nice pictures for such a
small critter.  Your specimen does appear to be Micromelo guamensis (based on
the shell - I have no idea what the soft parts of this species should look
like - or at least I didn't until now).
Finding a picture of this species in a book proved to be no easy task.  But I
did finally locate two books which illustrate this shell -
Marine Shells of South Africa by Steyn and Lussi (just published last year)
Hawaiian Marine Shells by E. Alison Kay
Interesting - the areas covered by these two books represent the extremes of
the geographic range of this species, and it appears in both of them.  Yet it
doesn't appear in any of dozens of books covering the middle of its range.
Regards,
Paul M.