I WONDER - Why Do Owls Make Pellets?

Owls consume prey but cannot digest certain parts like bones, feathers, and fur. These indigestible parts are compacted into a pellet by the owl's body, which is then coughed up to maintain the owl's digestive health.

What is formed from the undigested materials in an owl's body?

What action does an owl take to expel the undigested materials?