(Cross-post) Sonic 2 has an unused object that can be placed in Debug Mode (Edit Mode), which appears to be a spinning pole that acts like a Badnik: it hurts Sonic when he runs into it, and it explodes when he jumps into it. Based on that description alone, it's unclear what exactly this thing is meant to be, but I believe I've found a good explanation! Sonic 2, like Sonic 1 before it, groups its assets together in a logical fashion: in particular, it groups each zone's Badnik sprites separately from the rest of the zone's assets. Interestingly, the sprite for this unused object is not grouped with the zone's Badniks, but rather its non-Badnik sprites. Most tellingly, it is located right next to the zone's propeller sprites. Propellers spin, and the pole spins too... could it be? The sprites fit very well together. The 'pole' even has a pair of little sockets that the propeller sprites fit perfectly into: So why does it behave like a Badnik? That's because its collision type is set to that of an enemy in its sub-object definition. This isn't the only thing that gives it Badnik-like properties, however: the object also calls the 'MarkObjGone' function, which is used by objects which are capable of being destroyed and permanently removed from the level, typically Badniks. This, combined with the object's Badnik collision, suggest that this propeller was indeed intended to be destroyed by the player. The fact that this object is just a pole, and the propeller itself is an entirely-separate sprite, suggest that perhaps the pole would be the only vulnerable part of the contraption, with the propellers doing nothing but injure the player. This is all just conjecture, however. Neither TCRF nor the wiki mention the possible link between this unused object and the propeller sprites, so perhaps I'm the first to make this connection? Then again, the game's over 30 years old, so surely someone must have guessed this at least once, right?