>"most of the businesses and institutions who supply us"
What businesses would supply cadavers to cannibals??
https://www.ancient-symbols.com/masonic_symbols.html
Masonic Shoe – The Masonic shoe which is also called the Blue Slipper, is symbolic of a physical confirmation of a spoken deed. To unloose one’s shoe and give it to another person was the way of confirming a contract in ancient times.
Probably a stretch… but could this signify a completed exchange?