When most people think about extraterrestrial life they envision intelligent, often technologically advanced, humanoid creatures, such as the Prawns (District Nine) and the Na’vi (Avatar), robots, such as Gort (The Day the Earth Stood Still), and the hive-like Borg (Star Trek). Most astrobiologists, however, are not looking for intelligent life. They are looking for bacteria-like organisms. For as discussed in Section 5.2, microbial life is almost certainly far more common in the universe than complex multicellular organisms, let alone intelligent, technologically sophisticated creatures. Because they are so tiny, detecting and identifying extraterrestrial microbes is especially challenging.