A silver ball

For some very strange reason, Dusty loves aluminium foil. If I unroll some foil to use for cooking, he immediately comes running, no matter where he is or what he was doing. He also comes if we open a bar of chocolate wrapped in foil :)

I don't want him to have a sheet of foil but sometimes as a treat I carefully fold in the edges and create a ball. He'll play with it for hours until he loses it under something, or until Kuro steals it. Sometimes he runs around with it in his mouth, growling at Kuro.

 Above I wrote 'aluminium' which is British English. Americans use 'aluminum' which is simpler.