The Smithsonian National Museum of Natural History has a new exhibit up dedicated to x-ray portraiture of fish. All the shots were taken by Sandra Raredon, a museum specialist in the Division of Fishes (which is kind of a wonderful title, yes?)
I dig this because, on verbal description, this sounds rather dull. X-rays of fishes. Great. But when you actually see the images you remember two very important facts: First, fishes have tons of little, teeny bones packed into a relatively small body; Second, fishes come in a wide variety of frequently crazy shapes. That all adds up to fish x-rays being way more interesting than you might initially guess.
Take the scorpionfish. In real life, this family tends to look a bit like a bunch of Muppet trolls—runaway cast members from "Labyrinth" or something. In x-ray, you can see past the wild colors and stubbly, camouflage skin to spot the spines these fish use for delivering a numbing, toxic poison.
Check out all the fish x-rays at the Encyclopedia of Life.