I just found an index in a cave where there was a necromancer fiddling about. What does it do? Has it got anything to do with the large structures scattered across morrowind which usually have a couple of levels underground and 1 building on the surface containing two "things" with red stuff in the middle? (Behold and respect my descriptive abilities) ... you know what I'm talking about right?

What do I need the index for?

Yes,

they are keys to the teleportation devices in the strongholds.
I've found about 3 of them. there is one in the pawn shop in
Caldera.

They're just teleporters? That sucks.. I hoped it would be something cool, like a secret level or something.. with boots of blinding speed or enough speed-enchanted items, who needs teleporters? (those in the mage guilds are enough)

actually the indexes are ver useful most of them are usually right next to mission important ruins and stuff like that. they pretty much cover all the near by places the silt striders,boats,and mage guilds miss. unless you turn on godmode to make your scrolls infinite then (i.e. windform scroll gives levitate 500pts in godmode when you use scroll it stays after used so keep using it over and over)