Abstract Background The evolution of the brain and its major neuropils in Panarthropoda (comprising Arthropoda. Tardigrada and Onychophora) remains enigmatic. As one of the closest relatives of arthropods. onychophorans are regarded as indispensable for a broad understanding of the evolution of panarthropod organ systems. https://www.deliandiver.com/product-category/steam-nozzle/