It is the inside of a centrifuge where the rotor gets attached (the top spins, and the two pins ensure proper seat of the rotor on the conical piece). Here is a better picture of the inside of a Sorvall RC-5C Plus Floor Centrifuge, with the hands serving as scale bar. This is partially disassembled to show how one would change the motor brushing.
Screenshot from https://youtu.be/rO1q2eHTyJ0?t=434
If this is for a trivia game, I want to be credited. If this is for some crazy exam question, I'm sorry I helped cheating.