These things are dangerous. You get used to pounding on them, then you find the one that's max level (10 I think) and it beats you down to a sliver. Be sure to /con these as they can be anywhere from 4-10, and a level 10 will give you a run for your money at level 11.
These are low level (level one probably) just like the Decaying Gnome Skeletons. They are less common though, and can usually be found past the windmills (where there are no Decaying). What is their purpose? Placeholders for the tough regular skeletons I guess.
I was walking around Steamfont (looking for my micro servos :)) and I ran into a few of these on the road to the windmills. The conned green and threatening and with my usual bloodlust, I went after one. They fell apart with one swing of my mino axe (17 dam). When a newbie (um, a bigger newbie then me) was being chased by these things and there was no watchman to save him, I killed them again in one swing each. I sware it said Gnome Skeleton above them, not decaying Gnome Skeleton. Maybe a bug?