I can't believe that eggs from freshwater sells will survive in an old Cassis or Charonia. What I
think is that the shells or eggs came with different water plants in the aquarium (or on another
way, in a platic bag with water and fish), as they are not always visuable the first time.
So it happens and it was an accident together with these shells.
with best shelling greetings
Helmut from Innsbruck

Helmut "Helix" Nisters
Franz-Fischer-Str. 46
A-6020 Innsbruck / Austria / Innsbruck
phone and fax: 0043 / 512 / 57 32 14
e-mail: [log in to unmask]
web:    www.netwing.at/nisters/
           (please visit it and sign guestbook)

office:
Natural History Department of the
Tiroler Landesmuseum Ferdinandeum Innsbruck
Feldstrasse 11 a
A-6020 Innsbruck / Austria / Europe
phone: 0043 / 512 / 58 72 86 - 37

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I habitutally give inexpensive or "commercial" shells to pretty well
everyone i know, but the greatest surprise that has ever come from this,
came last week, when a friend came up and said "You know those big
shells you gave us a while ago?  Well, we put them in the kid's
aquarium, and now we have a pile of snails crawing around the place!"
Ok, i thought - what the heck is going on?
These were an ancient Charonia and Cassis cornuta from the Phillipines,
so i was puzzled in the extreme, until i saw the critters in question:
Fresh-water snails of the genus Physa.  However, i had had these shells
for a few years, and they had come from an old collection before that -
so assuming that once upon a time, they had been left in a stream for a
brief period of time, and had picked up either "hitch-hikers" or the
eggs of same, it had still been quite a number of years since this was
possible.  Oddly enough, the wee beasties cam in two distinct flavors -
completely grown (over 20mm, after having been in the tank for less than
2 weeks), and rather small (less than 10mm), which indicates that both
eggs and adults had survived in an aestivated form for at least 10
years!! (None have passed on yet, so i can't get a photo, but i don't
recall having seen this species in Nova Scotia, and in any case, Halifax
has notoriously acidic soil and water, being built upon granite and
slate: so, non-marine shell-makers are uncommon, except in gardens and
lawns, where a man-made alkaline condition exists.  So, they could not
have come accidentally from the stream which runs past their house,
which has 75mm spiders, but no Physa that i have ever phound.

I'd like to know whether it is an uncommon occurance for fresh-water
snails to survive in a dormant form for many years, and what is the
longest period known for the revival of same: has anyone ever left an
amphora from King Tut's tomb, for example, in a wash-basin, and found
3000 year-old snails the  next day?

Yours in The Wilderness of the Great White North,
Ross.