Here in Southeast Alaska we have been aging Geoduck Clam shells and Rock
Scallop shells using thin sections of the shell hinges for aging.  We are
also experimenting with Strontium mapping. Strontium is laid down in
heavier concentrations during the winters and a method called X-ray
mapping can show the relative concentrations of strontium as a digital
image. We have found Geoduck Clams ranging from 11 years to 81 years of
age. The Canadians found one at 130 years of age. This is the worlds
largest burrowing clam.
 
 -----Original Message-----
From: Conchologists of America List
Sent: Friday, June 26, 1998 3:52 PM
To: ScottW; [log in to unmask]
Subject: How old is that shell?
 
     Can you more experienced conchologists/malacologists out there
     help me with a few questions concerning the age of shells.
 
     1) I was wondering how long it takes most cones and cowries to
     reach their adult size?  That is when the shell is considered
     adult and no longer juvenile.
 
     2) Can you determine the age of a shell?  I know with some
     bivalves, you can count the number of growth lines to determine
     its age.  How do you tell the age of gastropods such as cones or
     cowries?
 
     3) Are giant sized shells very old shells or are they ones which
     just grew bigger?
 
     Thanks in advance for any and all responses.
 
     Ted Hu
     Montebello, California USA