It's hard to decide which of the colorful parrotfish's many unique characteristics is most remarkable.

There’s its diet, which consists primarily of algae extracted from chunks of coral ripped from a reef. The coral is pulverized with grinding teeth in the fishes’ throats in order to get to the algae-filled polyps inside. Much of the sand in the parrotfish's range is actually the ground-up, undigested coral they excrete.

There's its sex, which they can change repeatedly throughout their lives, and their coloration and patterns, which are a classification nightmare, varying greatly, even among the males, females, and juveniles of the same species.

Finally, there are the pajamas. Every night, certain species of parrotfish envelope themselves in a transparent cocoon made of mucous secreted