I know that Zim is 16 in Irken years and 159 in Earth years, I just want to know where that came from, or how we know that. Was it in an episode or something?
I do recall an episode of Zim being born... And that's in the first season when Zim's school was having an open house or something. But, it doesn't saying anything about how old he is. The producer talks about it in interviews stuff but not in the show.