TOS s2e6 “The Doomsday Machine” and VOY s5e14 “Bliss”
The telepathic pitcher plant was approximately two thousand kilometers wide, and contained large amounts of bioplasmic energy.
So, the giant cone is slightly larger in overall length than just the width of the “face” on the giant ship devouring mouth.
BananaVoyager for scale:
Well, I really wish there were no space fauna at all. Because it makes no sense, and I always rolled my eyes at those episodes.