The shell carbonate of pre- and post-bomb samples of 2 species of terrestrial gastropods (Theba pisana and Cernuella virgata) sampled along the coast of Apulia, southern Italy, were dated using accelerator mass spectrometry and carbon stable isotopes were analyzed. The analyses show, for both species, significant anomalies in the radiocarbon age due to the possible presence of a 14C-depleted source of carbon in the formation of the shell aragonite. The magnitude of the age anomaly was quantified in the studied area to ∼1000 14C yr.