My shoe stopped but my foot inside the shoe didn't. The sudden force of my toe trying to eject itself from the end of the shoe caused enough pressure on the toe nail for it to rip right off. It's the same momentum you get when a car suddenly stops but you're still ejected forward, except it's your foot inside an enclosed shoe. It was extraordinarily painful.
I've played a lot of sports in my time. My worst injuries were always from basketball. All the sprinting & sudden stops, jumping, I had to stop playing because of chronic shin splits. I can't jump anymore. So now I hike, bike, occasionally play baseball, swim, nothing that puts too much strain on the lower legs.
The toe nail grew back.