Cover

The invention discloses a cover which comprises a cover body, a first layer, a second layer, and a third layer. The cover body comprises a through hole, and the through hole comprises a first end anda second end facing towards an opening covering an item; the first layer comprises a manually coded graphic text with unique index information; the second layer includes patterns using natural materials, wherein the patterns can be identified by scanning; and after the cover is covered on the item, the constituent materials of the third layer include materials that can be melted by heating and solidified after cooling and particles that cannot be melted under the heating condition and can be mixed with the melted materials, and the third layer is formed by combining the materials after coolingand solidifying and the particles. The first, second and third layers are arranged in the cover body successively in an overlapped mode with the first layer facing the first end. The first layer, atleast part of the second la