All matter has a resonant frequency that is represented in this table by their spectral emission when observed via Spectroscopy. As you can imagine, some of these frequencies fall within the visible light spectrum. http://www.fieldtestedsystems.com/ A Microwaved Planet's photo. PeriodicTableSpectra http://www.fieldtestedsystems.com/
On land, animals leave footprints that tell us a lot about their size, form and capabilities. Marine organisms do this too, but these footprints are harder to see since water is translucent. Bioengineer Kakani Katija explains how she uses dyes, lasers and more to make them visible, so that she and her intrepid collaborators can understand more about how sea organisms move.