Opening A Portal To Hell And Releasing The Kraken!!

This is the coolest looking and possibly one of the scariest reactions you will see today or in a few days.

It looks like some gate to hell in open and the Kraken is here to destroy us.

But, in reality, what's depicted in the video below is actually two reactions: the decomposition of ammonium dichromate and the combustion reaction of mercury thiocyanate. The orange powder is ammonium dichromate and when heat is introduced, it forms nitrogen gas, water, and ammonium oxide, which is the dark powder that looks like the volcano you see. 

What appears to be tentacles is actually what happens when heat is introduced to mercury thiocyanate. The white solid expands when it's heated to become a dark, tentacle-like mass due to its decomposition to carbon nitride.