>  My Granddaughter was challenged by her teacher to find if there was any easy way to determine the age of a Conch and as a result, I'm looking for information dealing with external shell characteristics and their relationship to the age of the Conch.  I've found an article by Dr. Douglas S. Jones, http://erato.acnatsci.org/conchnet/jones893.html that deals with "Growth Rings and Longevity in Bivalves", but don't know if the general premise is also applicable to the Conch.<

I'm not sure if it counts as an easy way, but the general premise does apply to snails such as conchs.  However, the coiled growth form can make it trickier to examine the growth rings, especially if the later whorls largely cover the earlier ones.

One challenge of growth ring data is the risk that an unusually unfavorable season could produce an extra ring.  Rings represent times of slow growth, which could be winter for cold-water species, summer for warm-water species, or a season of the year when food is less abundant or less of a priority (the breeding season).  Detailed study of the appearance of the rings may discriminate between such possible causes.  In addition, there are chemical analyses that can be used to trace seasonal variations in the environment.  By taking samples along the direction of growth and analyzing them, these seasonal changes can be detected.
Shells are made primarily of calcium carbonate.  The carbonate in turn consists of carbon and oxygen.  Both of them have multiple stable isotopes that are reasonably common.  If all other factors are constant, the ratio of oxygen isotopes used to make the shell is a function of temperature. Both carbon and oxygen isotopes also can vary due to other environmental factors.   Thus, shells preserve a chemical record of the environment that they inhabited.  This will tell you if the rings correspond to times of high or low temperature or some other factor.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa