Watch this flowerpot create fire that burns underwater

This flowerpot full of red powder looks pretty innocuous. 

But when ignited with a strip of magnesium and a blowtorch, it yields a molten metal so hot it keeps burning underwater. 

The red powder in question is thermite, a mixture of finely powdered rust and aluminum that burns at a temperature of over 4,000 degrees Fahrenheit. 

In a video uploaded to his YouTube channel, TheBackyardScientist demonstrated what various metals did when he melted them and poured them into a fish tank full of water. 

For thermite, the result is liquid iron so hot water can't put out the fire: 

Once you get over the initial shock of what you're seeing, watching the fiery chunks of metal sink is mesmerizing. 

The silvery blobs you can see rushing upward are bubbles of gas formed when the water that comes in contact with the molten metal boils. 

As the iron slowly cools, chunks of it (and another byproduct, aluminum oxide) settle at the bottom of the tank, still shedding bubbles: 

Watch TheBackyardScientist melt other metals and pour them into water: