Coral skeletal extension rate: An environmental signal or a subject to inaccuracies?

► Sources of errors when measuring coral extension rates are identified and discussed. ► Measurements of skeletal extension rate do not reflect an annual time scale. ► Dissepiment spacing and number best reflect the annual time scale. ► Calcification rate can give information about how the coral “senses” its environment. ► We need to develop a method to accurately measure skeletal extension rate.