Numbers 4:12-14

and they shall take all the utensils of the service with which they minister in the sanctuary, and put them in a blue cloth, and cover them with a covering of porpoise skin, and put them on the carrying bars. Then they shall clean away the ashes from the altar [of burnt offering], and spread a purple cloth over it. They shall also put on it all its utensils with which they minister in connection with it: the pans, the meat-forks, the shovels, the basins, and all the utensils of the altar; and they shall spread a covering of porpoise skin over it, and insert its carrying poles.