A couple other replies mentioned appaloosas; I love their color changes! My foal was born in 2012, so I have 10 years of watching her colors change; although, color seemed to stabilize around 4-5 years old.

(I don’t post horse photos on Reddit anymore because I got some nasty, hurtful DM’s criticizing me for even owning mini horses and also critiquing their weight, which we’ve worked on pretty successfully with a good vet.)

Anyway, here’s a link to a photo I posted a few years ago starting with her suckling at a few months age (at top left) and ending with how she looked at 5 years old (bottom right.)

What especially fascinates me is what features came from which bloodlines. She’s grade (unregistered) as are her parents, but I have some scant knowledge from where she came.

Her sire, whom I still own is full leopard. Her dam (in that first photo) is ho-hum brown-colored.

Going a little back, the mare’s parents are a snowflake mare and a full leopard stallion.

On her sire’s side are mostly pintaloosa/leopard types. For example, my guys grand-sire is a pintaloosa as is his sire (no photo.)

Sorry if this was too long. TLDR, appaloosa colors are fun.