People who watch boxing, rugby, or mixed martial arts probably already know what cauliflower ear is. I had to learn from James Bond. Cauliflower ears, an interesting quirk of biology, are ears that have swelled up and collapsed until they resemble cauliflower.
In Diamonds Are Forever, James Bond goes to a bath house spa, and gets a mud treatment. While there, he sees a mob enforcer bust in and pour boiling hot mud over the face of an embezzling jockey. At twelve, I was not able to concentrate either on the weirdness of James Bond getting a mud treatment or the plot twist, because during the description of the spa, Ian Fleming mentioned that one of the attendants was a "man with a cauliflower ear." As this was before internet ubiquity, I spent quite some time wondering, "what the hell is that?"
What Fleming was trying to get across was that this was a bathhouse staffed by failed athletes, and the man was an ex-boxer. Cauliflower ears are ears that have been injured so repeatedly, and treated so rarely, that they both swell and curl in on themselves. Today's contact-sport athletes often have some degree of ear damage due to repeated injuries, but in the past ear injuries would go untreated for so long that they'd curl completely. Sometimes the ear canal would even get sealed off.
The process starts when the ear gets hit hard enough to separate the skin from the cartilage. This begins two processes. One is swelling. Like any badly-damaged area, blood and fluid flows in. The second is collapse. The perichondrium often comes away with the skin. The perichondrium is the layer of tissue that creates more cartilage, while providing nutrients to the cartilage that's already there. Without its support, the cartilage that's there begins to die, and the tissue collapses in on itself. The swollen tissue, meanwhile, doesn't always shrink back down. Some of the blood drains, but often the calcium remains, leaving hard deposits under the skin.
The best treatment, to prevent permanent damage, is immediately draining away the fluid and suturing the skin back down. Mostly though, prevention is what keeps the ear from collapsing. This is why people wear headgear with ear flaps. So they don't end up as a bit of color in a James Bond novel.