<There are many millions of Yeerks. And they can breed quickly when there are hosts for them. On this planet - I do not know, but tens of thousands, at least. Controllers can mimic their hosts perfectly if they wish, but Yeerks must leave their hosts once every -> He pauses to make some kind of calculation. <Three Earth days, to go into a Yeerk pool and feed on Kandrona rays, from their home sun or an engineered duplicate. Longer than that and they begin to starve.> He pauses again, main eyes shutting briefly, perhaps in pain. <If you have seen a bladed alien that was not my kind it was probably a Hork-Bajir. They are peaceful of themselves, but their world fell years ago and are now all infested by Yeerks. More Andalites like myself may come to help here but I know not when. And -> He holds his hand out for the blue box.