Chitin, a molecule that serves a purpose in the developmental biology of insects, fungi and shrimp, has long been a target of growth-inhibiting pesticides due to the belief that it did not exist in vertebrates. For decades, chitin-inhibiting pesticides have stunted the growth of insects and fungi to protect valuable crops. Now, research from the Wyss Institute has contributed to new findings that for the very first time reveal the presence of chitin in fish and amphibians, calling the environmental and ecological impacts of chitin-inhibiting pesticides into question. *Credit: Stained zebrafish and axolotl salamander images – W. Joyce Tang, Benaroya Research Institute at Virginia Mason