The orange powder is ammonium dichromate and when heat is introduced, it forms nitrogen gas, water, and ammonium (III) 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 (II) thiocyanate. The white solid expands when it's heated to become a dark, tentacle-like mass due to its decomposition to carbon nitride. In addition, sulfur dioxide and mercury (II) sulfide are also produced. The reaction is appropriately nicknamed the "Pharoah's Serpent" and was sold in stores as fireworks until people realized it's toxic.
TOF remembers those "fireworks." You lit up a pellet and a "snake" grew out of it and curled all over. He does not recall all the 4th of July dead bodies from the mercury thiocyanate, sulfur dioxide, and mercury sulfide, but supposes they must have been on the next block.