The Shift is a period of metamorphosis featuring major hormonal and chemical changes that the Frunalians undergo and is similar to the puberty of other species.
During the Shift, the skin of a Frunalian will toughen and the raised ridges on their shoulders, thought by many biologists to be vestigial wings, will disappear. A new sensory appendage appears as well, which grows from the brow and extends backward behind the skull and down the spine, resembling a "fleshy mane". In females, four mammary glands will mature along with internal sex organs.
Some Frunalians are unable to cope with the chemical changes brought about by the Shift and emerge from it a noticeably different person than they were before. Furthermore, some are so ill-equipped to deal with the chemical changes that they emerge from the Shift in a state of insanity. Knowledge of these events only make the Shift more stressful.
Due to the private nature of the Shift, most Frunalians choose to undergo it on their homeworld Orelte. (ST - The Lost Era novel: Serpents Among the Ruins)