© Glenn RogersWeird cloud formation, Perth Australia
Several PerthNow readers have woken to a sight described as "out of this world" after spotting a puzzling UFO-shaped cloud in the sky. The unusual cloud formation even had experts baffled, with the Bureau of Meteorology taking some time to investigate what the strange phenomenon may be.

Anyone fearing an alien invasion can now have their minds put at rest as experts at the Bureau of Meteorology have confirmed their original suspicions are true - the strange phenomenon sighted in Perth skies this morning was in fact a Fallstreak Cloud.

According to the bureau's Neil Bennett, the cloud - which was sitting high above Perth Airport - contained extremely cold water particles.

© Daniel James Hall
As air crafts flew through the cloud, the particles in their jet exhaust caused this extremely cold water to instantly freeze.

The newly frozen ice crystals inside the cloud became a lot heavier then the cloud itself.As a result, the heavier ice crystals fell through the cloud, leaving an usual hole - just like the one Perth locals reported seeing this morning. A Fallstreak hole is a cloud formation that gives the appearance of strange holes in the sky's cloud layer.

The unusual sight is causing quite a storm on Twitter with many locals continuing to speculate that the cloud may be evidence of something a lot more sinister.

Mr Bennett said: "It doesn't occur often so it's no surprise that it's causing quite a stir".