One snap does not make your dog aggresive and does not mean you should get rid of him.

Bones are a very high value item to dogs and all he was doing was warnng you to leave his posession alone, you ignored him so he reacted. But wheny ou marched back in, you obviously had confidence about you so he hade no move.

I agree with the advice above about introducing a bone but holding onto it.
The 'leave' command is a very useful one, so work on that with various items.

ps When I give my dogs a bone, they have it in their crates and are left alone to enjy it in peace. (also I don't want that all over my floor!) if I want them out of thei crates for any reason while they have a bone they are asked to leave it an the crate is locke to stop them bringing it out or stealing the other ones bone.

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