Why would the consort have the "key" to unlocking a vision about humanities past for a relic on a planet no where near Earth (http://masseffect.wikia.com/wiki/Eletania). It should also be noted that it is one of the things imported from a ME1 save game though it doesn't seem to have an effect on me2 or me3. It could be the levithans, or it could just be what it says and be the Protheans.
There are only two sphere type of devices known to be prothean. This one and the one from the firewalker DLC that adds it to the Normandy. Maybe it was protheans Leviathan controlled? Maybe it was technology the protheans stole from leviathan servants. It really is a mystery that isn't explained by the game. Or it could just be an Easter egg referencing 2001 a space odyssey.