The Newborn is a crossbred of Human and alien DNA. Most distinctively It has eyes, and a tiny little nose. It is grey in colour, and It thinks Ripley is it's Mother. This alien's birth was no different to any other alien. When the mutated queen lost her normal reproductive cycle, her grew a womb similar to a human and inside grew the newborn- which hatched rather spectacularly. But then the Newborn killed the Queen, because it did not believe that it was in fact it's mother, and so a possible threat. The Newborn thinks it is human and thinks for itself- it's not bound by the 'hive-mind' style heirarchy.