Okay, besides the Atro Forge and the Augur of Dunlain, there is a third object of interest in the Midden underneath the College... the Artifact, a hand with a Daedric "Oht" sigil in the palm, and each individual finger is frobbable for... something.

So what does it do?

Summons a Pirate Deadra, who is looking for his booty! Arrrrrrrr!

Have you tried talking to it?

its the rings from the missing apprentices isnt it?

He wants you to find his treasure idk much more though, had to go to work.

Yeah there in the chest in the library.

search for 'daedric relic' in the wiki to avoid any more spoilers. it has all the info.