Believe it or not, there are well over 4,000 different types of cockroaches—that we know about. Some estimates suggest we've discovered only about half the total number of species. Though most live in the wild, at least a few tenacious species have become uncomfortably common, extremely unwelcome guests in our houses and apartments. Curious about these creepy-crawly critters? Click through for seven astonishing facts you won't want to believe!