Figure 23.21: Molting, Past and Present (A) A 500-million-year-old fossil from the Cambrian captured an individual of a long-extinct arthropod species in the process of molting, demonstrating that molting is an evolutionarily ancient trait. (B) This tailless whip scorpion has just emerged from its discarded exoskeleton and will be highly vulnerable until its new cuticle has hardened.