Butterflies drink turtle tears to stock up on sodium

Believe it or not, Amazonian butterflies enjoy drinking turtle tears. Butterflies in the amazon get their sodium this way because its hard for the butterflies to find the sodium elsewhere. 

Besides obstructing their vision and making them temporarily more vulnerable to predators, it doesn't physically hurt the turtles when the butterflies sip on their tears.

The sight of a turtle with butterflies on its head brings me great joy, but the thought of drinking turtle tears does not.