The Ugly Barnacle/Nightmare Fuel

""That didn't help at all!""
 * 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.


 * Patrick was simply reading the story like any other cheery fairy tale, and ended it with a really, really creepy smile. Spongebob's reaction says it all.
 * If a mere barnacle can kill everyone, imagine what other creatures can do...
 * Some might view the story more as Fridge Horror than Nightmare Fuel. It can be a completely silly, nonsensical story, or a Cosmic Horror Story about a hideous Eldritch Abomination, 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 killed himself out of guilt and/or loneliness.
 * 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.