Among the amusing bits in the FF is the inclusion of the Booka. Household spirits who can play tricks on you are good for flavor and setting, but even as a young teen I thought that having stats for the things seemed... silly.
Equally strange is the Denzelian or, as a long-time watcher of the original Star Trek, the Horta. Like the Star Trek Horta, the Denzelian is primarily a plot device. Unlike the Horta, the Denzelian can't burn the crap out of miners.
While I can't fault the authors for trying to introduce the idea that monsters aren't just something to fight, the presentation of them as something to fight, just like all the monsters, only creates a weird sort of tension, a sort of "what the hell do I do with this thing" sense.
The Carbuncle, however, presents a basically useless monster with an interesting non-combat challenge. Carbuncles, apparently, grow rubies on their forheads. Kill them, and the ruby is destroyed. Convince them to let you take it, and they are fine. Abuse them, they will themselves dead. Spend time coaxing them to get the ruby, and they will mess with your head, trying to sow seeds of discontent among the party. Good times, there.