In Raiders of the Lost Ark, while the Ark is sitting inside a crate in the ship's hold we are shown that the crate mysteriously starts to burn, obscuring the swastika and other markings stenciled on its side.
Presumably it's the Ark itself that is doing this, since no one is around at the time.
Why does the Ark burn the crate? It evidently doesn't hinder the Germans finding it when they intercept the cargo ship shortly thereafter. The Ark's crate appears to be the only thing in the cargo hold.