Mastodon is sometimes referred to as progressive metal in the media (think Tool) which I don’t generally like. A lot of that stuff goes overboard on the chops at the expense of making music you actually want to listen to (Wynona’s Big Brown Beaver excepted). But I had read a bunch of reviews of their latest, Crack the Skye, that were intriguing: themes of quantum physics, transcendence, epic story, etc. so I bought it.
Long story short, I really highly recommend it, it is exceptional. It is the sort of content that you really get into after listening to it several times. It is extremely dense and complex without giving the feeling that the density and complexity is an end in and of itself. I found myself thinking that in some ways it has a Mercyful Fate / King Diamond-esque flavor in that it is an epic concept album (think Abigail) which has complex and haunting melodies combined with throat punching pro- reptile brain parts.
Go buy it clones.