* Everyone ''died''.
* Not only is the titular barnacle a being of intense, unfathomable hideousness, it is capable of committing ''total omnicide'', and does so by the end of the story, regardless of whether or not this was its intention.
--> ''"That didn't help at all!"''
* [[TheDitz Patrick]] was simply reading the story like any other cheery fairy tale, and ended it with a really, ''really'' [[SlasherSmile creepy smile.]] Spongebob's reaction says it all.
* If a mere barnacle can kill everyone, imagine what other creatures can do...
** [[NightmareRetardant Not much, since they're dead.]]
* Some might view the story more as FridgeHorror than NightmareFuel. It can be a completely silly, nonsensical story, or a CosmicHorrorStory about a hideous EldritchAbomination, depending on how you want to view it.
** In addition, if everyone dies, that means the Barnacle is included. So try to picture this for a minute: not only should he suffer the guilt of killing anyone, but also he died with no chance of redeeming himself. The logical conclusion is that to be killed by the Barnacle's ugliness, you must look at him. This means that Barnacle should have looked at himself in order to die, thing that doesn't happen accidentally. The most obvious conclusion is that the Barnacle [[DrivenToSuicide killed himself]] out of guilt and/or loneliness.
*** In furthering the FridgeHorror in this instance, you have to consider that the chilling line "Everyone died" meant that everyone excluding the barnacle died. So, in a sense, the barnacle is [[FateWorseThanDeath forever doomed to walk the cold ocean, completely alone, save for him and his own ugliness]]. And whenever he does meet another living being, they'll simply die upon sight of him. [[PsychologicalHorror Yeah]].
** Or... the Barnacle was killed by his own ugliness as soon as he was born. Think about it, you're so ugly that you instantly die along with rest of the living things.