 The gemmules then become dormant, and in this state can survive cold, drying out, lack of oxygen and extreme variations in salinity.Freshwater gemmules often do not revive until the temperature drops, stays cold for a few months and then reaches a near-"normal" level.When a gemmule germinates, the archeocytes round the outside of the cluster transform into pinacocytes, a membrane over a pore in the shell bursts, the cluster of cells slowly emerges, and most of the remaining archeocytes transform into other cell types needed to make a functioning sponge.