A unique subspecies of nerf—a nonsentient species—inhabited the Core Worlds planet of Grizmallt. This particular subspecies displayed several distinctions from typical nerfs, bearing a greater similarity to eopies and possessing antlers. In The New Essential Guide to Alien Species, an anthropological work derived from the observations of Senior Anthropologist Mammon Hoole, it was hypothesized that the Grizmallt nerfs had undergone physical adaptations, specifically in their body structure and neck length, over millennia, driven by the need to reach trees to consume berries and foliage for eat.
Ann Margaret Lewis referenced the Grizmallt nerf subspecies in her 2006 reference book, The New Essential Guide to Alien Species.