I checked my files, it should be there just like Jayfeather says its called containers.MATERIAl and if you open it with notepad it will have lots of text in there. Pay close attention to anything it says after the word Material. example, the first thing on that list is 'Material BottleJug'. write all those down and when you go into Object Mater, type in the mesh and when it pops up, in the text box below the mesh one you put BottleJug if its the bottlejug.