In the archaeological sites of the southwestern Iberian Peninsula small dumps of land snails are frequently found. It is likely that these deposits are the traces of human activity. However, it could also be possible that these dumps were produced by a natural process at a period of time when these molluscs were inactive. We will try to explain the origin of these snail deposits by undertaking a statistical analysis to test hypotheses comparing biometric analyses from different groups of snails: those collected by people who usually consume snails in 2009, those found in plants where these molluscs accumulate at the end of the summer of 2009 and those registered in several archaeological sites: “La Gallega” (2,500 BC; Valencina de la Concepción, Seville), “El Carambolo” (ninth-sixth century BC; Camas, Seville), “Cerro de la Albina” (seventh century BC; Puebla del Río, Seville), “C/ San Felipe Neri” (second-third centuries BC; Carmona, Seville), “Hospital de las Cinco Llagas” (twelfth century AC; Seville), “La Almagra” (twelfth century AC; Huelva) and “C/ San Fernando” (twelfth century AC; Seville). The biometric analysis and the biostratinomic observations have provided us a mathematical model to ascertain the origin of deposits of land snails in archaeological sites