DND_Reborn
The High Aldwin
ARISE, THREAD, ARISE! And LIVE AGAIN!
Welcome to the forums and have a like.Ok.. I see a lot of bad arguments for not having armor and natural armor stack. An elephant or even say a honey badger has thick tough skin. A natural armor. If I stick a layer of chain mail over that, that skin is not less hard to pierce and now before I can even pierce it, I have to pierce chain mail. I'd say they stack. Especially since the only actual natural armor example I can see in the books is a recalculation due to a druids wild shape. Something which has never stacked, in the first place as you and everything on you basically morphs into the animal. Not accounting for races with a natural armor class feels like a huge oversight by WoC, when looking at threats like these.

I always liked the idea of adding half value of armor to natural armor. So, an elephant in chain mail would gain a +3 to AC (half the +6 chain mail grants above 10).