Somewhere in the rivers and lakes of Europe right now, there is an eel that has been sitting in the mud for twenty years, growing slowly, eating whatever comes close enough, and waiting for something. We do not know what eels think about, or even if they think, or really much about them at all beyond the basic biographical facts, which are already so strange that the thinking part barely matters.
What we do know is that at some point, this particular eel will stop eating, its eyes will double in size, its belly will turn silver, and it will begin a four thousand mile journey to a specific patch of ocean in the middle of the Atlantic that it has never visited, to do something it has never done, after which it will expire.
No scientist has ever followed one all the way there. No one has ever witnessed what happens when it arrives. The European eel, Anguilla anguilla, has been confusing people for so long and so comprehensively that it has accumulated a hall of fame of baffled experts. Starting with Aristotle, but by 350 BC, a lot of things were still confusing. Sigmund Freud spent way too much time dissecting eels in search of their testicles. He cut open hundreds of them, only to be outsmarted by an animal that only developed the apparatus on the way to its own funeral. Or so we assume.
