So the other day I found myself unable to get anything else done until I had found out why sperm whales are called sperm whales, and it was worse than I thought.

Sperm whales are the ones with the gigantic boxy heads. Rather than having a nice aerodynamic silhouette like other whales, the sort of design that makes all modern cars look alike, they look like they have an entire shipping container in there, or God’s refrigerator. What they do have is a massive organ called the spermaceta, completely full of sperm, and it sits right on top of another organ called its junk. The blowhole is worn on the left.

All of that is true, except for the sperm part. It’s full of some waxy goo not quite liquid and not quite solid that looks like semen, and that’s what the ancient mariners thought it was, some kind of horrible buildup of jizz in the head, but it’s not. Nobody needs that much semen, and the whole ocean is already a wet spot. You’d think a bunch of seamen would know better but they got that part wrong.

The stuff is useful, though, and that’s the sort of thing that gets a species in trouble. You drill into one whale and you’ve got yourself around 530 gallons of stuff you can burn for light or use as a lubricant. Of course you’re going to use it as a lubricant, when push comes to shove, and you’re on a boat with a bunch of other men, and nobody cares if the lights are on.

Sperm whales have by far the largest volume of waxy crap in their heads among all mammals not running for public office. So why the hell does a whale get boxy and unaerodynamic and stuff his head with something like semen and something called its junk?

Surprise! No one knows.

Which delights me. This ain’t no minor beast. Sperm whales not only have the largest brains of anyone, but they’re also the loudest animal in the world. I am much energized by the sheer volume of stuff we don’t know anything about, after pressing our big brains to the task for hundreds of years. And maybe we’re used to the idea that we can’t see dark matter but just intuit it must exist; and maybe we are confused about what some extraneous pincer on a random insect is for; and maybe no one knows when the anus evolved, although we have a good idea why. But not knowing what ol’ Big Box Brain is doing with a gargantuan chamber of faux spunk? Shouldn’t that be figure-outable? Not knowing is so much more satisfying than knowing it all. The world retains its mystery and everything we do find out has a way of producing more questions. Ain’t that grand?

The old seamen thought they used it to cushion themselves whilst ramming ships. They did ram ships, but likely did not evolve their refrigerator heads for that purpose, due to a dearth of ships fifty million years ago; so maybe they rammed each other like bison. A group of scientists developed models of whale heads and rammed them at each other to see where the mechanical stresses were and the results indeed suggest that might be a function. Male sperm whales have been observed only once in the act of ramming each other, but, as scientists have pointed out, a lot of things whales do is underwater, and we might miss it. But why would the female whales have the same shape rather than something more slimming?

Other hypotheses include that the big head o’ goo is involved with buoyancy, or might have hydraulic functions, or—and this is considered most likely—helps in echolocation. Which is handy if you’re planning to dive to the bottom of the ocean to hunt squids in the dark. Which I’m not, and that is good, because my head is very very small.