Ah, I see! In that context, "I saw some of your residues" is not a scientific term. When someone says "I saw some of your residues", they mean they saw traces, remnants, or leftovers of something you did, used, or left behind. Here are some examples of what it could mean: Physical traces: If you were eating, they might have seen crumbs or a wrapper. If you were working on something, they might have seen tools or materials you left out. It could be a mark, a stain, or an item you forgot. Figurative traces: Less commonly, it could refer to the lingering effects or atmosphere* you left behind in a place, though this is more poetic. Essentially, they observed evidence that you were there or had done something.