I've been reading a lot of Douglas Adams lately

So, apologies to his estate, and all that.

The Val'Ahr'Ahrin of Trepanis V are a willowy, telepathic people who are unique in the universe as they are the only alien race known to eat poetry and excrete literary criticism. This is to say that their highly developed telepathic brains draw sustenance from rhyme and meter, metaphor and simile, image and verse. This is to say further that as a byproduct of the process of digesting poetry, the Val'Ahr'Ahrin excrete a substance which is entirely indistinguishable from dogshit.