Dungeons & Dragons: 1st Edition Monster Manual (part 2)
Zack: Holy crap, would it ever suck to be one of these things. You spend hours slowly crawling around a cave and climbing up the wall and positioning yourself on the ceiling. Then an adventurer walks underneath you and you drop...and miss.
Steve: Or worse, you hit them, but you don't do much damage.
Zack: Yeah, what then? You've got one shot and then you're pretty much dead. You're a big cone with a mouth and eyes.
Steve: Piercers have always bothered me. If you follow the rules they still take falling damage, so if the ceiling of the cave is too high they could die just from the fall. Like, even if they killed whatever they were aiming for, they could still die.
Zack: My terrible life as a kamikaze ice cream cone.
Steve: And what about a baby piercer? What does that eat?
Steve: No, I mean really little ones. Like newborn piercers.
Zack: Maybe it falls into bowls of stalactite milk.
Steve: I don't think these are mammals.
Zack: Wait, these things live in caves and you've established that caves are identical to subterranean labyrinths. Could they be owlbears?
Steve: Could you be a butthole?