Cotylorhiza tuberculata, collected in late summer off the Apulia coasts, showed high variability in size (Figure 1, Table S1). The specimens ranged from about 6 cm to nearly 30 cm in bell diameter; the oral arms and tentacles usually expand beyond the increase in size of the umbrella. The mature organisms (with gametes or larvae), reached considerable size and mass, as showed from the weight/diameter ratios, which ranged from about 3 to 61 in younger and mature individuals, respectively (Table S1).