The Hrud are a
subterranean and evasive race, and their technology is based on plasma, an
example being the Plasma Fusil. A unique concept behind the Hrud is that
they exist in a temporal dimension outside our own. Because of this it is
theorized that they are able to phase in and out of their planes to further
infest areas. They were supposedly all but cleansed by the Iron Warriors
during the Great Crusade.
Many have named Hrud the 'Space Skaven', as there is a common popular
conception of Hrud being the 40k equivalents to the Rat-men from Warhammer
Fantasy known as Skaven. However, this is as yet unproven. No reliable canon
images or backround material has been produced that supports this. It's
pretty hard to find out anything about Hrud in general. More recent fluff
released has given the concept that the Hrud are based off the Jawas and
Tusken Raiders raiders from that of Star Wars because they are supposed to
have originally come from a desert world and that they are small and shadowy
looking creatures who drape themselves in rags and cloaks. Another addition
to this assumption is that they travel using large transport vehicles
similar to a sandcrawler.