The above image shows an example of how your pet will change as it grows up over time. Most pets will be fully grown in 30 days, sometimes much faster.
These rodents may grow up into different adults by random chance - each newborn usually has a chance to grow up into around 1 - 4 different adult versions, and some might be very rare! Make sure to adopt more than one and watch them change as they grow.
The hamster and guinea pig linearts were drawn by sketchi, and the rat linearts were drawn by Tess.