The sunflower sea star is a big starfish — more than 3 feet across — that roams the ocean floor in orange, yellow and purple. These invertebrates can grow as many as 24 arms, and they’re ...

But even though the earliest traces of starfish stretch all the way back to the Paleozoic era, they're not a sea creature ...

This story appears in the June 2011 issue of National Geographic magazine. The sea star—often called a starfish, though it's no more a fish than it is a sheepdog—ranks with the most ...