Monomyth released back in '09 as FFF's third album. The other two releases weren't really anything too spectacular and there's a six year gap between this and the second album, so I'm guessing this is where they decided to try and develop an album that would drive people nuts. Quite frankly, this album does that to me - in a good way.
Fin Fang Foom is a post rock band that features vocals, which is something not that typical in the genre. This album is melodic in some ways, but still has this amazing progressive heaviness throughout that sucks you in. The song, "Lonely Waves" is an amazing example of this where you can hear both sides of the album in one.
There's nothing I can really say negatively about this album and I think it's an underrated masterpiece that more people should look at. Post rock essential? Maybe. It's definitely worth the listen though.