Just read an article on the makeup of everyday products we all use. It was an eye opener to say the least.
Cow's intestines are used to make the strings of tennis rackets and harp strings. The poor cow's horns are turned into buttons, their bones into china, and along with the leather from the hide, their hooves are used in the manufacture of fire fighting foam.
The undigested squid vomited up by sperm whales - is found in several high-end perfumes. A serum made from sheep placenta can be applied to the face as a beauty treatment. Chitin - a substance found in shrimp shells - is used in many hair products such as styling gel.
However the worst one in my mind is Isinglass. This is the swim bladder of some species of fish which is used as a fining agent for some beers - helping to ensure the final pint is clear rather than cloudy.
Now that is a step too far.