I finally got around to exploring the ideas and moves of the 19th century German philosopher Arthur Schopenhauer, and in his most famous work, In The World as Will and Representation, discovered this passage, which is supposed to present the ultimate example of strife in the world, the utter cruelty of existence, the deadly force of the will to live:

Many insects lay their eggs on the skin and even in the body of the larvae of other insects, whose slow destruction is the first work of the newly hatched brood. The young hydra, which grows like a bud out of the old one, and afterwards separates itself from it, fights while it is still joined to the old one for the prey that offers itself, so that the one snatches it out of the mouth of the other. But the bulldog-ant of Australia affords us the most extraordinary example of this kind; for if it is cut in two, a battle begins between the head and the tail. The head seizes the tail in its teeth, and the tail defends itself bravely by stinging the head: the battle may last for half an hour, until they die or are dragged away by other ants. This contest takes place every time the experiment is tried.

This is the mean insect Schopenhauer had in mind:
I have no idea if it’s true that the bulldog ant, if separated, fights with itself. But that doesn’t matter. What’s important is the “extraordinary example” itself, the fact that a bulldog ant’s self-battle gets to the essence of Schopenhauer’s pessimistic philosophy. (The talking triangle is Spinoza’s “extraordinary example,” and Hume’s is the robot in a forest clearing.)