From Creatures Wikia
The Micro Grendels are a Grendel breed created by Trix. They were Trix' first succesful attempt at making a truly different C3 genome. As such, these tiny Grendels are very different from normal Grendels. They don't care much about Norns or Ettins, but they love to socialise and slap, slapping being a crucial mating ritual for them. They're also egg crazy and difficult to hurt. You can download them at the Universe of Ettins.