Pteria sterna is an eastern Pacific pearl oyster of commercial value from Peru to central Baja California, Mexico. The continuous presence of this species in San Diego for a decade is unique as it is approximately 600 km north of the expected range for the species. A minimum of three generations are present in Mission Bay at any point in time and the preferred substrate for attachment are gorgonian corals. The species is also found off shore in cooler water. The continued presence of this oyster raises the question as to the status of this population; is it a permanent range extension or simply a transient population and what has changed that allowed its continued presence?