Following the discovery, users flocked to comment how the deadly toxin was "everywhere" at the moment.
From the front of the bed everything looks fine - but the couple wanted to be sure so pulled it out from the wall. Photo / Facebook
Mattresses, bases and wooden frames are hotbeds for mould, with some residents saying they only discovered the infestation after they upgraded their bed.
"We upgraded our bed and turns out the bottom of the mattress was all mouldy!" one user said.
The fungi thrives in damp or water-damaged environments and can cause serious health issues if inhaled.
One resident flipped over their mattress to find it covered in black mould. Photo / Facebook
Symptoms of mould exposure include increased risk of asthma, allergies, respiratory infections and coughing.
Australian residents are urged to stop mould in its tracks by using a dehumidifier, opening windows and doors when the weather permits and checking leaky roofs and walls for the toxin.
Stores across Brisbane sold out of mould killer last week as flood-ravaged homeowners attempted to detoxify their homes.
One man even revealed the bare supermarket and hardware shop shelves in a social media post, with another user commenting, "In this day and age you have to be one step ahead of the panic buyers."
A Brisbane Bunnings spokesperson told NCA NewsWire that the store had been running low on mould killer concentrate but still had plenty of pre-mixed options.