behemoth of hydocarbons

Behemoth (Hebrew בהמות, behemot; Arabic بهيموث bahīmūth, or بهموت bahamūt) is a creature mentioned in the Book of Job, 40:15-24.

The word is most likely a plural form of בהמה (bəhēmāh), meaning beast or large animal. It may be an example of pluralis excellentiae, a Hebrew method of expressing greatness by pluralizing a noun; it thus indicates that Behemoth is the largest and most powerful animal.

Metaphorically, the name has come to be used for any extremely large and powerful entity.

I like that end bit "extremly large and powerful entity".