As a C. elegans hermaphrodite progresses through its lifecycle, it has several opportunities to stop or delay its growth and maturation. A notable example is the alternative larval stages known as 'dauer''. In this state, worms are ultra stress-resistant, extremely long-lived,  and highly mobile, yet they do not feed and they cannot reproduce. Worms enter this state in response to various stresses and can exit when conditions improve, progressing to adulthood and reproductive maturity. They have made a reversible trade-off between survival and reproduction. The 'hows' of this are largely known, but the 'whys' are somewhat taken for granted. What is the fitness advantage (if any) in that plasticity? What is/are the driving forces? Are there really energetic trade-offs? Many questions remain to be answered and with modern genetic and cell biological tools, we can address them. The answers have implications not only for nematodes, but for all species, including humans and may underlie some of the deepest mysteries surrounding why we age.