Yes, you read that correctly. Cello Metal Band. Just try to wrap your head around that concept :)
For those of you who are not familiar - here's a taste of what Metallica sounds like:
And this is what Apocalyptica sounds like playing Metallica:
Fun Fact: Apocalyptica also was the band who had made the music for Rovio Entertainment ( Creators of Angry Birds ) for one of the Angry Birds Seasons episode - On Finn Ice .