The following utensils protect with a sealed cover: Dung utensils, stone utensils, clay utensils, earthenware utensils, nesser utensils, bones of a fish or its skin, bones of a sea creature or its skin, and wooden utensils that are tahor. They protect both from their mouths and from their sides, [and] whether they are resting on their bases or tilted on their sides. [If] they were turned over upon their mouths, they protect all that is beneath them down to the depths; R’ Eliezer rules it tamei. [These utensils] protect all things, except for an earthenware utensil, which only protects foodstuff and earthenware utensils.