Holly,

Great question.  I have often tried to figure out the single shell I would
keep and failed -- but ten, now that is a player.  However, I think a color
series of a single species is kind of cheating -- yeah, I know, who's game
is this anyway?!!

My candidates, from among my collection (not dream shells I may never have)
are:

Murex (Chicoreus) aculeatis (or M.artimis or M. nobilis, your choice)
Nerita chamaeleon (an elegant specimen with a grey background and dark
markings)
Guildfordea yoka (near perfect)
Epitonium rugosum (classy)
Xenophora pallidula (an old favorite)
Cypraea rosselli (not a great "window" but a wonderful shell none-the-less)
Voluta delessertiana (cheap but one of the dressier volutes)
Oliva porphyria (a classic)
Marginella sabastiani (had to have one for Bob & Betty)
Mitra filiareginae (a beaut)
Conus amadis (elegant)
Terebra pertusa (unbelievable coloring)
Thacheria mirabilis (if it astounded the experts, who am I to argue?)
Chlamys imbricata (and these live under rocks!)
Harpa ventricosa cabriti (better gloss than any Cypraea)
Cymatium succincta (parallel lines anyone?)
Murex (Chicoreus) palmarosea (elegant if a bit over-stated)
Pleurotomaria gotoi (a bit doctored but a beaut)

And there you have the ten shells I would carry out in case of fire or
whatever.  For those of you who do not trust my count, all I can say is I
get ten every time I count them.

Tom Eichhorst in New Mexico, USA