For some reason this makes me think of how fish pick at debris that collects on sharks and whales, to keep the larger mammal clean and free of infection, so both animals can continue living their lives.

I wonder if the larger animal is even aware of the army of fish it takes to keep it from succumbing to disease and decay.

TIL Symbiosis requires the two members to be of different species https://en.wikipedia.org/wiki/Symbiosis#Cleaning_symbiosis