Their is a Gelatinous Cube named CUBERT that spawns in the aquaducts, approximately level 15. He drops a dress which can be used to get the golden ear stud or some other items in a quest!!!
I went down with my mage at lvl 8 and had most of the cubes con blue to me. And actually had one con Red to me at lvl 8. So they at least go up to lvl 10.