title_body: unique agglutinative root system? The language of The Old Ones is described as "an agglutinative speech
  with root systems utterly unlike any found in human languages" (H.P.
  Lovecraft, "The Shadow Out of Time", Chapter 4). What techniques
  could a conlanger use to devise a unique root system for an
  agglutinative language?
upvoted_answer: In my opinion, it reflects, if anything, more on Lovecraft's lack of linguistic understanding than anything about the language of the Old Ones, since the roots in human languages get pretty damn ridiculous, so it's really hard to imagine something "utterly unlike any found in human languages". You would have to design a phonology produced by speech organs completely unlike those of humans to approach this.
  
  Where I to tackle this, I would go for a system not unlike Arabic, but where the root is constituted of a set of vowels instead (with maybe "consonant harmony"?).
  
  Alternatively, Mark Rosenfelder's Kebreni has roots where vowels are swapped around a whole lot, and I doubt that metathesis as a base derivational system exists in any human language.
  
  Generally, I'm not sure designing something literally outside the boundaries of what the human mind can handle is by definition possible, which is what Lovecraft truly was after in his poor description attempt.