I'm new to the site, a few days actually. Well, I noticed that there is a level part in the creatu's info. Anyone know what that is or how to level up a creatu? And at what age to they grow to adolescent? Adult?

Hello! 
Leveling up was probably meant to be when we had a battle system on this site. It's being re-coded at the moment though and as far as i'm aware there's no way to level up your pets. 
You can however raise their stats through various items :D 
For example you can raise a pets intellect by reading it books

A pet will grow to adolescence at age 15 and adult at 30 

Thank you! This was very helpful!