It was made "for fun" last year.
The theme tune from ‘Rick and Morty‘ got a metal makeover at the end of last night’s episode.
The metal version was aired during a special post-credits sequence following the eighth episode of the third season, titled ‘Morty’s Mind’.
The track was made by producer Jason Suecof and drummer Alex Rüdinger.
‘Rick and Morty’ co-creator Justin Roiland tweeted: “The awesome metal version of the theme song was done by @jasonsuecof“.
Suecof Instagrammed a screenshot of Roiland’s tweet, with the caption: “@alexrudinger and I are beyond excited about our metal Rick and Morty theme being in last nights episode!!!!!
Rüdinger revealed on his Instagram that the track was made “for fun” last year when he was doing a session job at Suecof’s Audiohammer Studios.
He added: “It’s truly SICK that it got used in an episode. Been a BIG fan of #RickAndMorty since its inception!!”
The show’s writers recently shared a list of freaky, unused ideas from a recent episode, that were “too weird” to actually get used.
Meanwhile, fans have been coming up with theories about Evil Morty, who first appeared in season 1, episode 10.