Ok so we all know about the "helmet" that gets stuck in there, i managed to release one-i was so surprised i have now forgot how i did it, think it was with magic as i seem to remember it blowing off the rock and falling down. Anyway i have returned and it has respawned to what looks like a different sort of helmet.
One i got was Orcish with an enchantment, thos looks to have the same enchantemtn but could be Ebony or Elven-hard to tell.
Anyone have more to add to this or any clues as to how it can be released-i tried telkineisis but that failed this time..........

you could try shooting a fireball with it, the area blast usually sends stuff flying