The deceased animals used for demonstration in this video were sustainably sourced and legal, as are all of my specimens. No animals were harmed for my purposes, most died by natural causes. If you have a problem with dead animals, I don't know why you're here!
Edit to add: Shortly after I made this video, I started using a full respirator. Formalin fumes can burn your nasal lining over time, and it's better to be safe than sorry! Always research the proper PPE for the chemicals you choose to use!