http://www.comcast.net/articles/news-science/20090122/SCI.Fish.Mystery/
Researchers believe they have solved the puzzle of three seemingly different fish, one all males, one all females and one all juveniles. They're the same fish, and undergo remarkable changes as they mature. "You can imagine it was a pretty exciting discovery," said G. David Johnson, an ichthyologist at the Smithsonian's National Museum of Natural History. "The pieces kept falling into place."