I heard from probobly an unreliable source that they drop off megaladon in IoD. i have no clue if this is correct or not. i wanted them for my nec as well, and asked around where to farm them, megaledon is the answer i got. instead of the soul gems my nec now has one dull red orb and the eye of narticus. look the same so i guess in the end i got what i wanted lmao, idk...