There's a shark and a jellyfish and they've lost their oar. They don't need a porcupine!
Well, if the whole thing is a metaphor for the inside of my head (which it sort of is), there ought to be a porcupine.

But you're right: they really don't need it (and I don't either).
Because that's a pretty good visual metaphor for how the inside of my head feels like right now: all prickly and spiky and not particularly conducive to accomplishing the things I need to do.