We present results from excavations at several shell midden sites in the region of Bajamar-Jatay, along the northwest coast of Baja California, Mexico. The morphology of stone cooking features is discussed in connection with potential uses and associated faunal remains, which indicate a diet based on the exploitation of nearshore marine resources. Under the assumption that differential consumption of harvested food resources may have influenced the type of heated stone structures used for cooking and processing, we suggest that the morphological differences between heated stone features are not random. The structure and style of a heated-rock cooking feature may be related to the types of foods that were prepared and the methods used to cook them. Ethnographic information supplements the archaeological data provided here and further supports our interpretations.