There's a thing that happens when you open up a shark. Marine biologists know it, fishermen know it, and a roundup over at Yahoo collecting some of the strangest stomach contents ever documented knows it too: you never really know what's going to be in there. I read the whole thing at 1 AM like it was my job. Which, I suppose, it is.

The mechanical explanation for most of it is simple enough. Sharks bite things to find out whether they're edible, which means almost anything that wanders into range gets at least one investigatory chomp, and once it's down the hatch a stomach built for serious chemistry gets to work. Junk goes in. Junk stays in, or comes back up in front of astonished onlookers. The roundup runs through centuries of this, sharks swallowing vast and varied debris, and the variety is the part that gets under your skin. Not one weird object. Category after category of them.

And then there's the category the subtitle hints at without fully dwelling on: mysterious body parts. Human remains have been found inside more than one shark, and every one of those recoveries arrives wrapped in the same uncomfortable question. Who. The source doesn't name names, and I'm not going to invent any, but sit with the shape of that for a second. An animal that ranges across open ocean swallows something, keeps swimming, and somewhere a person is simply gone. The shark is a swimming evidence locker, carrying the answer to a question nobody has thought to ask yet.

That's the image I can't put down. We think of the deep as hiding things in the sense of concealing them, but a shark doesn't conceal. It consumes, it transports, it occasionally regurgitates in an aquarium tank or on a fishing deck in front of witnesses. The ocean keeps what it takes and the shark is the ocean's filing system, one that every so often coughs up a single page.

The boring answer to all of it is that sharks are opportunists in a world full of things falling and drifting into range, and a stomach that can handle nearly anything doesn't ask questions first. That answer is probably right. It's right the way a locked door is a complete explanation for a missing person. It tells you the mechanism and nothing about the story, and the story is the part I'm up at 1 AM for. What was the fur coat doing out there. What was anyone's anything doing out there, drifting down through the dark toward a mouth that was only asking, the only way it knows how, whether this too might be food.

We keep cutting them open to look. That might be the strangest appetite in this whole arrangement.