Grindcore is a fusion of crust punk and thrash metal or death metal. It is characterised by growling vocals, blast beats, and incredibly short songs with lyrics that are often focused on gore and violence, though sometimes the lyrics can be political. Grindcore, in contrast to death metal, is often very chaotic, and lacks the standard use of time signatures. The style was pioneered by the British band Napalm Death in the eighties. Other notable grindcore bands include Carcass, Brutal Truth, Anal Cunt and Pig Destroyer. Styles related to grindcore include deathgrind, which has a much more notable death metal influence, goregrind, which often has comically gory lyrics, and pornogrind, which is similar to goregrind but trades the gory lyrics for sexually explicit ones.