Lol. But I don't understand, it's not really the height that counts, as long as the tank is over 12 inches tall. It's more of width, since they can get 12 inches all around, right? So if I could get a tank that was 3 feet long, 2 feet wide, and 18 inches tall, that would be sufficient, wouldn't it? Especially if I got a small urchin, so it would have time to grow.