GOD!!!!!!!
Lord Worm doesn't even grunt, he growls, he just gets a different sound. If you guys define growling by weather the singer pronouces their words perfectly so they're audiable (Like Opeth) your severly mistaken. I dont know of many vocalists that grunt (Alienation Mental maybe???) but mostly they either stick to doing the cleaner, for even vibrating growls or the lower more gutteral gurgling growels. The techniques for both are the same its just what part you use to project the energy and how it comes from the mouth.
Lord Worm had one of the best techniques for growling ever recorded. Simple. Grunting if anything is where the singer doesn't engaged any vibration or ripping and ends up making airy burping noises. Sheeeesssh!!!!