Growth of the lagoon cockle, Cerastoderma glaucum Poiret, was determined from samples collected seasonally from Keramoti lagoon in Greece in the northeastern Mediterranean. The three-dimensional almost “spherical” shell shape does not change throughout the life of the species. Foot length, flesh weight, shell, and total weight increased at a lower rate than shell size, whereas water content of the soft party decreased with growth. Condition index showed a strong seasonal variation. Flesh weight and flesh water content were among the body parameters examined that have a large influence on the physiological state of this bivalve. Burrowing ability of the species was examined in relation to type of sediment. Burial time was positively correlated with shell length in all types of sediment tested. C. glaucum is a substrate-specialist slow-burrowing species and it showed a clear preference for the sediment where it occurs naturally.