Palmer explains that he wrote this book because so many people he encountered were interested in what he does as a marine biologist. In truth it is a book about scientific curiosity and the process of discovery. I won't give away the ending, found in the last chapter. Had Palmer's objective been an exposition on biological clocks, the last chapter would have been first. Unfortunately, I already knew what was in the last chapter, so my appreciation for the book was somewhat dulled. Still, it is a short, well written, fairly entertaining book. Palmer does an excellent job in describing experiments and making them interesting, and in showing how often a verification of the obvious led instead to new paths of discovery. Not least, while Palmer's sense of humor is not terribly creative, he can be fun.