Foo Fighters countdown - what does it mean?

A countdown timer has appeared on the Foo Fighters' official website. Photo/AP

A mysterious clock has appeared on the website for rock act the Foo Fighters, but no one seems to know what it's counting down to.

The clock appeared yesterday and seems to be counting down to an event on Monday.

https://t.co/pFmFGUJgsX pic.twitter.com/zydmJICfdf

— Foo Fighters (@foofighters) October 29, 2015

Fan speculation varied wildly, including a new album or EP, a second season of Sonic Highways, another Super Bowl halftime show, or even a countdown for front man Dave Grohl getting the cast on his broken leg removed.

@LaLaLauraNicolo @mitchellneubert just run around and scream like Dave in preparation

— Corey Halliday (@Conny_McLane) October 29, 2015

@foofighters It better be a new song and not just an announcement of "Sonic Highways 2" in the making, cause we all already know that part..

— Dan Solo (@punkwaste) October 29, 2015

@foofighters can it be true? Foo Fighters at the Super Bowl!!

— Brett (@OsbornBrett) October 29, 2015

The Foos' current tour ends on November 19.

- nzherald.co.nz