Since limestone contains very little, if any, radiocarbon, clam shells will contain less radiocarbon than would have been the case if they had gotten their carbon atoms from the air.
This gives the clam shell an artificially old radiocarbon age.
If radiocarbon lasts only a few hundred thousand years, why is it found in all the earth’s diamonds dated at billions of years old?
It is not difficult to see how such a claim could arise, however.
Many people have been led to believe that radiometric dating methods have proved the earth to be billions of years old.
We will see that carbon dating strongly supports a young earth.
Thus, it is possible (and, given the Flood, probable) that materials which give radiocarbon dates of tens of thousands of radiocarbon years could have true ages of many fewer calendar years. The shells of live freshwater clams have been radiocarbon dated in excess of 1600 years old, clearly showing that the radiocarbon dating technique is not valid.
The shells of live freshwater clams can, and often do, give anomalous radiocarbon results.