What animal or insect leaves a shiny metallic residue?

The animal that often leaves a shiny metallic residue is the common green lacewing larva. These larvae, known for their predatory nature, excrete a shiny, metallic substance that can be mistaken for a form of protective coating. Additionally, certain species of beetles, like the jewel beetle, can also leave behind a shiny, metallic residue due to their reflective exoskeletons.