Lets learn about ferrofluid! Check out that link. Great stuff, eh?
Please correct me if I’m wrong, Ferrofluids are liquids that are filled with teeny tiny magnetic particles.
That was easier to explain than I thought. I really hoped to be more informative.
In the video they are using electromagnets. So to make a spiral, they create a cone tower and turn up and down the magnetism in the levels of the cone.
The spikes come from the strength of the magnetic field in any area. Its like each base ares of magnetism is pulling towards it all the fluid it can grab, and that fluid build and builds upwards until the force of the magnetism is so weak it cant support any more, and as the amount of fluid increases, the force weakens, and creates a cone shape.
For more technical descriptions, please do read the links.
Also, it evaporates!
The Wikipedia page is full of big words. Impress your friends like my friend impressed me.