a wood chipper? why would you need one of those on your robot?
Waveguide for the death beam?
It looks too me like they welded a mounting plate to a hollow bar ( hence the holes) then are just looking into the bar. Maybe for the arm.
I see a mounting plate on the near end (holes are the giveaway) with some type of wheel/chain-type thing inside, which I’m assuming is for some type of telescoping arm. Hmm…
I love optical illusions