I think it would be great for some more sequential joke pets!
First is the "flying golfball dogs" where the newborns seem like they are a picture of land from a high place (golf ball in mid air). Then with the different growth stages, the pups would be a closer look to certain spots to the landscape (golf ball falling). The clue where they will land is hidden in the scenery they are getting close to. The final adult stages would be where they landed. One could land in a sand pit, another in a tree, and another on the green! The others could land in a hole (lucky shot!),or end up underwater! This can be applied to other pets if desired. This one could be fun to do!

Next is "albatross crash landing"! Newborns start with a clear landing strip drawn on them. As they land in the young stage, the scenery gets flipped in odd ways! The adult stages will undoubtedly result in some messy pets! Some minor bruising and scratches possible amidst all the mud, sand, and weeds they picked up on their not so grand landing. Don't worry they should be fine! (minus a tooth here and there)
Next one could be "going shopping"! Pets start out as cage textures with a door in the middle. The next stage could be different isles of the supermarket with some goods in the cart! The adults would be full of various items brought depending on which isle their younger stage was. Lets hope they all avoid the snack isle...
I'll add more as they pop in my head later. Have fun guys!
