Experts have sound the alarm over silent alien invaders wreaking havoc in Aussie backyards that could cost homeowners thousands, as shocking footage shows a 5.5m monster torn from a tank.

And they’ve placed some very popular species on the garden terrorist hit list for those likely to cause significant damage.

This as nightmarish alien-like tentacles of a massive root system that seized control of an enormous water tank was exposed by tendrils that burst out the roof, forcing homeowners to destroy the entire system.

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Elliot Aisthorpe of Big Country Earthworks shared jaw-dropping footage of him pulling out a behemoth two-storey high monster out of th

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