I read on a forum that the Fallen Vandals have two genders. The males have two reproductive organs, a big one and a small one... and the females have one singular sexual orifice. Apparently females must receive penetration from both male organs to fertilize their eggs. They then rip open a pocket of flesh to remove the eggs so the males can carry them in their egg sack until they hatch. I don't know if this is true or not. I would like to get a response from Bungie explaining the Vandal mating process in detail.