Black Sabbath released their debut album on Feb. 13, 1970, ushering in heavy metal, which, 50 years later, has shown no sign of slowing down. In celebration of the milestone event, a number of rock and metal artists have posted about the album's anniversary on social media.

Almost unanimously regarded as the first-ever heavy metal record (though we debate that here), Black Sabbath offered something so unique and different from anything else in existence at the time, despite loads of other bands inching toward a heavier style of music that distanced itself from rock 'n' roll as this new style would eventually bear a term all its own.

Fittingly, Zakk Sabbath (Zakk Wylde's Black Sabbath tribute band) are playing a concert in Sabbath's hometown of Birmingham, England tonight (Feb. 13), to commemorate half a century of metal. If Tony Iommi isn't playing those riffs anymore, someone has to — thanks for your service to the almighty riff, Zakk!

See what members of Black Sabbath, Anthrax, Exodus, Sons of Apollo, Sepultura and more had to say about the 50th anniversary of Black Sabbath below.

Black Sabbath

Tony Iommi (Black Sabbath)

Geezer Butler (Black Sabbath)

Zakk Sabbath (feat. Zakk Wylde)

Scott Ian (Anthrax, The Damned Things)

Gary Holt (Exodus, Slayer)

OzzFest

Frank Bello (Anthrax)

Overkill

Mike Portnoy (Sons of Apollo, The Winery Dogs + a lot more)

Blasko (Ozzy Osbourne)

Andreas Kisser (Sepultura)

Rock and Roll Hall of Fame

Black Sabbath Songs Ranked Worst to Best (Ozzy Osbourne Era)