If you think starfish with 4 or 6 arms are weird, wait til you realize that there are species with 10, 20 and even 40 arms! Out of the 2k starfish species, the most common variety is the one with 5 arms. Which is why they're what you most often see in cartoons (remember Patrick from Spongebob Squarepants?), drawings, movies, and photos.

Oh, and in case you were wondering, some scientists are pushing to rename starfish as sea stars because they're, well, not fish!