Vivarium holds a rather unique system when it comes to those under a year. To help reduce some timeline that comes with playing children and the long-wait between, there is a system in place where those under a year are growing 2x speed, and grow on a stalemate until officially, on their birthday. So with every month, their body and mind develops for two months. We understand this can be generally confusing for some people, so we are now offering a a timeline to help parents and their litters.