This is actually one of my medical assistants that was having fun in Mexico and went for a swim a little too close to the reef, and boom sea urchin impregnation! Little ocean porcupine broke off a single crystal of calcite, a mineral mostly consisting of calcium carbonate. These little splinters can move to the surface or continue to dive deeper and pierce vessels or nerves, so it’s important to remove them all. Even a small piece can cause considerable pain or damage. Ocean acne. Reef blackheads. Salty pops! West coast blackheads. 😉 MrPopZit.