The aim of this book was to develop a method for analysing the seasonality of the European Oyster, Ostrea edulis. Patterning, in the form of growth breaks or bands in the shell micro-structure, has been shown to occur in other molluscs and has sometimesbeen used to ascertain the season of gathering for archaeological samples, but until now this has never been attempted on Ostrea edulis. The objective was to apply the method to oysters from Danish shell middens (køkkenmøddinger) in order to obtain information on the season of gathering at these sites. This is a particularly interesting area of Mesolithic studies as it is believed that the Ertebølle culture was a socially complex society of hunter gatherers, living off abundant coastal resources which enabled them to lead a sedentary existence. What is also of major importance is that through objects found, such as pottery and axes, it can be demonstrated that the Ertebølle people had contact with the farmers in the south, and yet agriculture was not adopted for 1000 years. Why such a long time lag exists has fired many debates and oysters have played a significant role in some of these.