Researchers introduce a novel imaging method to detect gold nanoparticles in woodlice. Their method, known as four-wave mixing microscopy, flashes light that the gold nanoparticles absorb. The light flashes again and the subsequent scattering reveals the nanoparticles’ locations. With information about the quantity, location, and impact of gold nanoparticles within the organism, scientists can better understand the potential harm other metals may have on nature.