Clan Vv3, a hacking group specializing in hacking celebrity accounts with bigoted (NSFW) content are responsible.
https://twitter.com/mastodonmusic
MASTODON unleashed "Once More 'Round the Sun" 6/24/2014 via REPRISE RECORDS.
MASTODON TWITTER ACCOUNT SCREEN SHOT:
7/17/2014 UPDATE 2PM EST USA: MASTODON HAVE REGAINED CONTROL OVER THE BANDS TWITTER ACCOUNT:
FROM MASTODON: I'm sure you noticed our account was compromised last night. Apologies for that. We're back in business now.
Thanks-Stay Metal, Stay Brutal-\m/ -l-