It is a Hell-beast born of fire!
Actually, it is a reaction caused by igniting a mixture of Mercury(II) thiocyanate (Hg(SCN)2) and Ammonium chromate (NH4)2CrO4, two highly toxic but highly awesome compounds. The video below of the reaction was uploaded to YouTube by Albert Schweinstein.
When lit, the chemicals spew fire, then around 30 seconds in they spring to life. Watch what happens:
The Ammonium chromate creates the volcano-like fire. The octopus effect comes from the Mercury (II) thiocyanate decomposing.
Decomposing Mercury thiocyanate is sometimes called Pharaoh’s snakes and, yes, the experiment can be done at home (be sure to wear proper protection and take necessary safety precautions).
Beware though — both substances are toxic in all forms. If you handle them at all, you should probably know what you are doing, and don’t breathe the fumes.
The Mighty Pythons toy you played with as a kid produced a pretty similar effect, but was made from a non-toxic material.
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