If this water is in contact with significant quantities of limestone, it will contain many carbon atoms from dissolved limestone.
Since limestone contains very little, if any, radiocarbon, clam shells will contain less radiocarbon then would have been the case if they had gotten their carbon atoms from the air.
There is not a single Nature only knows adaption, and adaption only occurs within species. And the very same is true for the non-existing concept of “dark energy”.
Adaption is always a response to a changing environment. By simply deleting these two absurd fictions, all the theories of scientism start to crumble.
A number of stories are commonly circulated about a shell, or a piece of coal, or some other sample which supposedly yielded a radiocarbon date which could not possibly be correct.
The truth is that (external) evolution does not exist. Clearly, this fictitious “dark matter” only exists in the science fiction world of scientism.This gives the clam shell an artificially old radiocarbon age.This problem, known as the "reservoir effect", is not of very great practical importance for radiocarbon dating since most of the artifacts which are useful for radiocarbon dating purposes and are of interest to archaeology derive from terrestrial organisms which ultimately obtain their carbon atoms from the air, not the water.In actual practice, it is the amassed evidence of multiple radiocarbon dates, generally on different materials by different investigators using different measurement apparatus, which is applied to a given chronological question.
Stories of the sort above, which are obviously meant simply to discredit radiocarbon dating, are very far from the truth.This is evident first of all by the fact that it is part of a date list which is broken into three parts: "geologic samples", "archaeological samples", and "fossil animals".