This chapter describes the blue moon phenomenon, the effect of anomalous aerosol light scattering, and the red tide and dead fish event caused by dinoflagellate and Gymnodinium brevis. Various studies on rhythmic leaf movements, circadian rhythm, and their control by the endogenous biological clock are presented. The chapter also discusses the incidence of bioluminescence in Gonyaulax polyedra, its mechanism, what causes it, and clock control. The role of melatonin in rhythms, biological rhythm research, and the circadian clock of Gonyaulax and its knowledge and usefulness are emphasized.